Being able to crank an attack up to eleven has a downside too. Sure it can end up being drastically more devastating than an un-prepped attack, but it can also be interrupted by those un-prepped attacks it seems so greatly superior to. Back on the star wars site where I got my start in writing combat RP, I'd go up against jedi and sith masters with epic force powers equipped with armor and some guns, and 9 times out of 10, their built-up force attack of utter devastation was made completely useless by a bullet to the head. And even if they avoided the bullet, they still had to break their concentration and lose a lot of the energy they were gathering for their charged attack. 

Point is, there are ways to defeat prepped attacks that don't involve a defense that opposes them directly. Unless the T1 rules on interrupting a prep are very different from what I'm used to... In which case I'd love it if someone could point out the correct methods involved. :)