A Stalker dictates the initial strike. This means before the battle has started, it has already moved in favor of a Stalker. It is harder, but not impossible due to ranged attacks, to do the same with a Blaster.
A Stalker can do the minimum for a mission. Again, a Blaster could do the same, but it will take more effort to do so, and a Stalker can do it at level 1.
Stalkers have built in mitigation. Even if a Blaster can get similar or equal amounts of mitigation in the end(Incarnates), a Stalker gets it much earlier.
"What about ambushes?"
And? I get what Hide offers, but considering most of the time I'm attacking isn't while in Hide, then not having it isn't a big deal. I'm more annoyed if I'm trying to Stealth for speed reasons and I'm forced to fight, but again, a Blaster doesn't have an advantage here either.