There was a bit of a discussion about this just the other day in skype, but what it comes down to is that it takes a lot of practice to master with rather little reward. That time could be put to better use, and the tech itself, while flashy, is also kind of gimmicky, as there's not much practical application. After all, all the tech does is allow you to do an aerial while you have a bomb/other item in your hand, which really isn't as good as it sounds. If it was, you'd see not only TL's, but other characters who can produce items abusing the tech left and right. As it stands, the only character to my knowledge whose mains often use aerials while holding an item is Peach, and that's because she can do it just by using her float (rather than doing an IZAC), which is much, much easier to do, and even then it's not like being able to do this makes Peach a good/better character anyway.