I have a lot to say about this, since the Churches that i have been visiting for my whole life sort of require an unspoken dress code and that's all the people need to turn it into a Gucci and Versace show.
But, as you've said it here, trying to be a normal conservative attire, is what the Church priests say too, but due to different cultures and countries, people sometimes go overboard and think it's a place to promote their latest styles.
Personally i wear a suit and tie when i'm at work, but when i go to the church i don't wear a suit and tie. That would be too much. I dress like i didn't roll from bed or i'm not the best man in the wedding either with a $2000 tuxedo.
So, like you said, try to be as normal and conservative as possible and for the people who don't have the money to wear nice clothes, there's nothing wrong either because it's not a 5 star restaurant. It's a Church.