But then you also find people sitting on the ground at Jesus' feet in whatever they wore every day of the year and it didn't matter.
A spiritually healthy church will reflect all aspects of God's character: His high majestic holiness and His intimate ease.
Actually, another 50 years and polo shirts may be the definition of "dressed up".
As we know, Jesus had the most resistance from the religious leaders, who simply were incapable of distinguishing between their traditions and the Word of God, and were willing to murder God rather then see their traditions eroded. Every generation has them; they look back one or two generations and lament the loss of the old ways, which to them looks like the loss of piety entire, because they don't have the eyes to see the wineskin which is this generation's form for distributing wine.
The gospel never changes but everything that is not dead will. Traditions are good, they give our forebears a vote -- if it is treated as a storehouse of tools from which the church draws, and not as a straitjacket which we may not toss aside if need be.
Much of this is just the old debate about what defines the church. The 2nd and 3rd generation solved the problem of instability by defining the church by the bishop, which was fine, but as "stability" evolved into "control" they refused to concede that God could make bishops out of stones if He wanted and that the transmission of tradition from one generation to the next is both good for stability and useless to guarantee the Presence.
Because the church is defined by the presence of the Holy Spirit, and He has been known to appear in tradition and in innovation, any Christian group whose concern is to defend "tradition" is off center. Period. Even though those traditions may be good and helpful.
I say this as a Wesleyan worship leader who always leads the service in a shirt and tie. And if we went by my taste, we would throw out those modern, casual hymnals and do Bach and Gregorian chant.
But that's my taste. David danced before the Lord. I'll betcha one street of gold that when he did he dressed down.