It would make more sense if there was a way of accessing the player's clothing inventory via the API but there isn't, so any clothing equipped on the player through the mod would be stuff that they don't actually own, and it wouldn't be permanent. I could implement outfit saving for the player like I did for NPCs, but then you'd have 2 separate wardrobes.
Edit: After testing it seems that calling dress() with specific clothing items does permanently add them to your inventory. This creates other problems though. Aside from the fact that you're getting free clothes, there's no way to determine the clothing stats like when you buy them from the store, so what you end up with is random. The game also doesn't check to see if you already own an item when using dress(clothing_item), so every time the function is called in that manner it's adding a new item to your inventory even if you already have it, which means it wouldn't take long for your wardrobe to be full of dozens or hundreds of the same items