I get that the item set builder (which is honestly an amazing feature that literally saves you time buying items and gets you back to lane faster) isn't used by a lot of players, but it could be cleaned up so easily and make for a better experience with probably just a few hours of coding. My main gripe is the presence of items that can't actually be purchased in-game.
Case in point: Items like zephyr, force of nature, and innervating locket which were removed long ago. This isn't just a matter of irritation; it brings back all kinds of memories of using those items, and now they sit there, taunting me with their presence, reminding me that I can no longer use them. I used to stack 3 or 4 zephyrs on Hecarim and proceed to run around the map at a million miles per hour and it was the greatest thing ever.
The items in the item set builder should match the items players can actually purchase. Please either bring those items back into the game or get them off the list.
Plus, if you cleaned the item set builder up, I bet more people would use it.