It's just you. 
Seriously answer:
Mental Blast on Blasters is the typical tier2 power in just about ever way. Will Domination (and any power that is not a tier1 or tier2) is not bound by the forced activation time, so it's activation is pretty much irrelevant.
Is Mental Blast's activation longer than Will Dominations? Absolutely. But as a non-tier1(2) blast that has no bearing.
Fireblast's activation is also longer than Blaze's. Ice Blast's activation is longer than Bitter Ice Blast. Hydro Blast's activation is longer than either version of Water Jet.
Edit: Now, on Defenders there's more room for debate, as Mental Blast is a terrible tier1 that every /Psi Defender gets saddled with. Can we please swap this out for Psionic Dart already?
@Oathbound & @Oathbound Too
Will Domination's cast time is a little better than the blaster tier 1/2 standard, but that comes with a grossly excessive recharge time that begs for PPMs (damage scalar 1.24
I'm surprised you didn't mention anything about Telekinetic Blast. That's the DPA outlier of the blaster version of Psi Blast.
Is it me or are the activation time for these powers reversed?