At least, imho I agree that MBS needs to be used carefully. Personally, I'd support the side that's against making macro too easy. Just being able to dig my hands into the big picture makes the game fun. (1)
But what makes SoaSE different, imo, is that it's HUGE, and even with simplifying macro, and even micro, there is plenty to get my hands into to keep busy. (2)
(1) Just thought I'd follow up a bit on my earlier comments. It's not that WCIII isn't balanced - it's that the gameplay isn't as diverse (my earlier post kinda seemed to imply this after I read over it a bit). All the exciting stuff happens with 1 or 2 CTRL groups AT the battle itself. Expansion is downright boring compared to Starcraft by pretty much anyone's standard.
Starcraft has a 'balance' of strength between micro and macro so that a player can max out on one or the other or have some mix in between to get different 'combinations'. The situational analysis in Starcraft is worlds beyond WCIII simply because ALL of WCIII is the micromanagement of individual battles.
You wanna build more units? Put your 4 barracks into a CTRL group, hit that CTRL key during a fight and press some hotkeys, then switch back to the battle (1-2 seconds have elapsed). Not even a thought is given to something like this. In Starcraft, you have to take your attention away from everything else in order to macro more successfully. The largest contributing factor, though, to WCIII 'smallness' (i.e. no 'big picture' to be found) is the harsh army size penalty and the small unit cap. All these things tend to remove 'real' macro from the game.
So while some people may prefer the micro-heavy style of play, I personally favor the micro-macro balance. The implication of all this, by the way, is that the interface is a CORE part of a game's balance. Consider the 12 unit selection limit in SC, and the 150 unit limit selection in SC2. That simple effect is going to make worlds of difference and change pretty much the entire game simply because of the choices for CTRL group management.
Again, sorry for more slightly off-topicness.
(2) I think you are onto something there. Sins does have a 'bigness' about it. The main thing that is 'big' about it, though, is the amount of time you have to actually execute things. Speed of execution is marginalized to a grand extent in this game. The pace is less furious, although not any less exciting (in my opinion). It really gives you that turn-based 'sit back and think' kind of feel because the utter scale of everything allows you to think thoroughly and still act quickly enough. There's not really any furiously dexterous CTRL/TAB/hotkey wizardry going on at any time. Units move very slowly and predictably, movement paths are finite, the economy is automated to a large extent, and the progression of power in the game is fairly linear (in terms of research). It all really boils down to that nebulous idea of 'strategy.' They did a pretty fair job cutting the 'fat' of execution from the game and focusing on the strategy.
I don't think there is really any kind of issue with MBS and such. The game itself was designed around the whole idea of eliminating the execution of micro and macro. It's very interesting, and they've been able to come up with a truly kickass interface (in terms of its usefulness) since they are not 'hindered' by any kind of micro-macro balance constraint. The only juggling or voodoo done here is situational analysis.