Because BT's look so awesome. I have a couple loose ones, and honestly, they're not as good for playing with because the joints become loose easily. But they look


Getting them all won't be that cheap though...completing them won't be that much cheaper than a set of TFC's. I think I have Masterpiece Prime, Ultra Magnus, and two trailers in my spreadsheet under BT's, so the total is just about the same as my total for TFC's.