While it's true that you probably don't want to wear your couture robes or bespoke suits when you're exploring sewers and dungeons, or mucking about in the untamed wilderness, there are times when it pays to look good.
Now, there have been some weird fashions over the years. Take these for example.
Kind of crazy... On the other hard, D&D is full of crazy, so really, not so out of place. But not everyone wants to look like that.
Here are a few examples of modern takes on what I would describe as quasi-medieval style.