This game is all about abilities. That's why these tt boosts don't mean much. Doesn't really help if you can boost a 95 to 99 when he still has bad and expensive abilities. An ability tt discount boost would be fire.
Instead of stats boost give at 15 -1, 30 -2, 45 -3 and 60 -5 ap on all abilities of your tt. Of course that would make older cards more valuable which is something they def don't want. That's why they got rid of power ups