From the BDAG. Which by the way disagrees with you. I highlighted in bold the section that applies. Bauer says it could mean either do, carry out, or as bring to full expression=show it forth in its true mng., or as fill up=complete. So it is not as conclusive as you claim unless one considers the context. Robertson in his work which follows the BDAG excerpt, comes to a conclusion. Please take a look.
BDAG.....a prayer (Chariton 8, 1, 9 πεπληρώκασιν οἱ θεοὶ τὰς εὐχάς; Aristaen., Ep. 1, 16 the god πεπλήρωκε τ. εὐχήν [=prayer]; IBM 894, 8 of answered prayer) πληρῶσαί μου τὴν αἴτησιν answer my prayer ITr 13:3 (cp. Ps 19:5; TestAbr A 15 p. 96, 4 [Stone p. 40]). A command(ment) (Herodian 3, 11, 4 τὰς ἐντολάς; POxy 1252A, 9 πλήρωσον τὸ κεκελευσμένον; 1 Macc 2:55; SibOr 3, 246) πεπλήρωκεν ἐντολὴν δικαιοσύνης Pol 3:3. νόμον (Ps.-Demetr., Form. Ep. p. 12, 9; cp. Hdt. 1, 199 ἐκπλῆσαι τὸν νόμον) Ro 13:8; pass. Gal 5:14 (but s. 3 above and cp. Aeschyl., Ag. 313). τὸ δικαίωμα τοῦ νόμου Ro 8:4. πᾶσαν δικαιοσύνην (cp. 4 Macc 12:14 πλ. τὴν εὐσέβειαν) Mt 3:15 (s. AFridrichsen: Congr. d’Hist. du Christ. I 1928, 167–77; OEissfeldt, ZNW 61, ’70, 209–15 and s. βαπτίζω 2a, end); pass. ISm 1:1 (s. δικαιοσύνη 3b). Also ἐστὶ πρέπον πληρωθῆναι πάντα it is fitting that all things should be fulfilled GEb 18, 40 (cp. APF 3, 1906, 370 II, 7 [II A.D.] ἕως ἅπαντα τὰ κατ᾿ ἐμὲ πεπληρῶσθαι).—A duty or office βλέπε τὴν διακονίαν … , ἵνα αὐτὴν πληροῖς pay attention to your duty … and perform it Col 4:17 (cp. CIG 2336 πλ. πᾶσαν ἀρχὴν κ. λειτουργίαν; PFlor 382, 40 πληρῶσαι τὴν λειτουργίαν; ISardRobert I p. 39 n. 5).—Abs., in the broadest sense and in contrast to καταλύειν (s. καταλύω 3a): οὐκ ἦλθον καταλῦσαι ἀλλὰ πληρῶσαι Mt 5:17; depending on how one prefers to interpret the context, πληρόω is understood here either as fulfill=do, carry out, or as bring to full expression=show it forth in its true mng., or as fill up=complete (s. AKlöpper, ZWT 39, 1896, 1ff; AHarnack, Aus Wissenschaft u. Leben II 1911, 225ff, SBBerlAk 1912, 184ff; JHänel, Der Schriftbegriff Jesu 1919, 155ff; Dalman, Jesus 56–66 confirm; WHatch, ATR 18, ’36, 129–40; HLjungman, D. Gesetz Erfüllen, ’54; WKümmel, Verheissung u. Erfüllung3, ’56; JO’Rourke, The Fulfilment Texts in Mt, CBQ 24, ’62, 394–403).
Robertson's Word Pictures in the New Testament states, "I came not to destroy, but to fulfil (ουκ ηλθον καταλυσα αλλα πληρωσα). The verb "destroy" means to "loosen down" as of a house or tent (2Co 5:1). Fulfil is to fill full. This Jesus did to the ceremonial law which pointed to him and the moral law he kept. "He came to fill the law, to reveal the full depth of meaning that it was intended to hold" (McNeile).
Let's look at the context
Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.
(Mat 5:17-20 KJV)
First if the Law is not destroyed it is still around in one sense or another.
Second heaven and earth are not passed away.
Third we are still here in this fallen world so all has not been fulfilled.
Forth we are warned not break or teach man to break even the least of these commandments.
So with all that in consideration an honest interpretation of the context must agree with what Robertson concludes. That Jesus "came to fill the law, to reveal the full depth of meaning that it was intended to hold"
BDAG.....a prayer (Chariton 8, 1, 9 πεπληρώκασιν οἱ θεοὶ τὰς εὐχάς; Aristaen., Ep. 1, 16 the god πεπλήρωκε τ. εὐχήν [=prayer]; IBM 894, 8 of answered prayer) πληρῶσαί μου τὴν αἴτησιν answer my prayer ITr 13:3 (cp. Ps 19:5; TestAbr A 15 p. 96, 4 [Stone p. 40]). A command(ment) (Herodian 3, 11, 4 τὰς ἐντολάς; POxy 1252A, 9 πλήρωσον τὸ κεκελευσμένον; 1 Macc 2:55; SibOr 3, 246) πεπλήρωκεν ἐντολὴν δικαιοσύνης Pol 3:3. νόμον (Ps.-Demetr., Form. Ep. p. 12, 9; cp. Hdt. 1, 199 ἐκπλῆσαι τὸν νόμον) Ro 13:8; pass. Gal 5:14 (but s. 3 above and cp. Aeschyl., Ag. 313). τὸ δικαίωμα τοῦ νόμου Ro 8:4. πᾶσαν δικαιοσύνην (cp. 4 Macc 12:14 πλ. τὴν εὐσέβειαν) Mt 3:15 (s. AFridrichsen: Congr. d’Hist. du Christ. I 1928, 167–77; OEissfeldt, ZNW 61, ’70, 209–15 and s. βαπτίζω 2a, end); pass. ISm 1:1 (s. δικαιοσύνη 3b). Also ἐστὶ πρέπον πληρωθῆναι πάντα it is fitting that all things should be fulfilled GEb 18, 40 (cp. APF 3, 1906, 370 II, 7 [II A.D.] ἕως ἅπαντα τὰ κατ᾿ ἐμὲ πεπληρῶσθαι).—A duty or office βλέπε τὴν διακονίαν … , ἵνα αὐτὴν πληροῖς pay attention to your duty … and perform it Col 4:17 (cp. CIG 2336 πλ. πᾶσαν ἀρχὴν κ. λειτουργίαν; PFlor 382, 40 πληρῶσαι τὴν λειτουργίαν; ISardRobert I p. 39 n. 5).—Abs., in the broadest sense and in contrast to καταλύειν (s. καταλύω 3a): οὐκ ἦλθον καταλῦσαι ἀλλὰ πληρῶσαι Mt 5:17; depending on how one prefers to interpret the context, πληρόω is understood here either as fulfill=do, carry out, or as bring to full expression=show it forth in its true mng., or as fill up=complete (s. AKlöpper, ZWT 39, 1896, 1ff; AHarnack, Aus Wissenschaft u. Leben II 1911, 225ff, SBBerlAk 1912, 184ff; JHänel, Der Schriftbegriff Jesu 1919, 155ff; Dalman, Jesus 56–66 confirm; WHatch, ATR 18, ’36, 129–40; HLjungman, D. Gesetz Erfüllen, ’54; WKümmel, Verheissung u. Erfüllung3, ’56; JO’Rourke, The Fulfilment Texts in Mt, CBQ 24, ’62, 394–403).
Robertson's Word Pictures in the New Testament states, "I came not to destroy, but to fulfil (ουκ ηλθον καταλυσα αλλα πληρωσα). The verb "destroy" means to "loosen down" as of a house or tent (2Co 5:1). Fulfil is to fill full. This Jesus did to the ceremonial law which pointed to him and the moral law he kept. "He came to fill the law, to reveal the full depth of meaning that it was intended to hold" (McNeile).
Let's look at the context
Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.
(Mat 5:17-20 KJV)
First if the Law is not destroyed it is still around in one sense or another.
Second heaven and earth are not passed away.
Third we are still here in this fallen world so all has not been fulfilled.
Forth we are warned not break or teach man to break even the least of these commandments.
So with all that in consideration an honest interpretation of the context must agree with what Robertson concludes. That Jesus "came to fill the law, to reveal the full depth of meaning that it was intended to hold"