It requires a lot more than that to change an LX over to a GT. There's way too many differences between the LX and GT for anyone to put out a kit that could build either one. It's something that just isn't feasible. The nose piece, rear bumper (no, you can't just add cladding to the LX bumper), tail lights, body molding, wheels and tail pipes are all different between the two. Then you have the differences between the interiors.
I didn't realize there were that many differences. Well, I suppose you could do a 2-in-1, but it would take a fair number of extra parts.
I still wouldn't be shocked to see something come down the pike, though.