Fair enough playtime > mission counts, im assuming SCII missions will be like warcraft III, their most recent RTS which was excellent and definately had enough playtime, blizzard havent dissapointed yet.
And maybe I will be wrong, and EACH SC2 product will be as time consuming as WC3 (it has been years since i played that... makes mental to replay WC3 this spring/summer). I find that my pessimistic predictions are usually quite accurate, and maybe even a little optimistic when compared with the eventual results (at least when it comes to project budgeting and scheduling).
I do not want half of those 90 missions to be tutorial missions, but one thing that occurs to me is a need for a very "basic" (i.e. easy, watered down, but still good enough to be addicting) RTS that is more of an LONG tutorial game. The extremely young and extremely old gamers (is that ageist?) who have never been exposed to a good RTS game need a game (or series of games) to teach them what a RTS is all about. The Wii is exposing virgin gamers to computer (console AND PC) gaming, but there needs to be something to bridge the gap into overly complex computer gaming.
As an example, some EBgames employee recommended Backyard Baseball (he did not even have it instock, but was honest enough to recommend it) as an intro in a baseball sports game for a grandfather with limited gaming experience. These "easy" games appeal to the old as well as the young. That was years before the Wii.
A certain popular MMO has been watered down for the "RPG virgin" masses, but has now disappointed many early adopters. [DDO (next on my personal MMO list to try) still seems complex, though I am not sure those abandoning WoW have been clued in to DDO's current status.]
Or are there already a bunch of "My Little Pony" and "SpongeBob" RTS games out there?