I suppose the 'overkill' idea with MiTB is slightly different, like Kaedon mentioned.
MiTB was (and I think still should be) a once a year spectacle. It's the one time where a guy like Edge or Swagger can step up their game. It has purpose, and a real nice feel and build to it. The idea of doing, not only as a PPV theme, but to have two matches in it, is overkill. It kills it's relation to WM, and really doesn't feel like it's "his" turn to step up. Worst off, they'll have to use big stars. So really, it'll just be a six-man ladder match, with No1 Contenders stips.
The difference to the HiAC/EC overkill is - those matches were used for a purpose. They were used (more so HiAC/Cage/LMS) to build/end a fued. You didn't just have two guys face eachother once then ... oops, we HAVE to fight next time in a HiAC. Darn. It was once 'HBK/HHH fued hatred was intense enough, that it needed to end in HiAC.' Now, it's just a gimmick. It doesn't mean anything, at all.
Sucks, really.