Evolving StarCraft meta

I don't claim to be a pro gamer or anything (cuz I'm not), but I do like the game of StarCraft.  It seems like only the pros can play super greedy - why, because their micro is fantastic?  That would make sense only if there were an exceedingly high threshold for micro being useful.

The fact is, the AI is pretty f*cking stupid.  Even if you're in Bronze league, micro can be helpful.  And remember: pros are playing other pros, whose micro is just as good as theirs is.  So I really doubt that it's micro.  But I genuinely don't know why it is that pros, playing against other pros, can be more greedy than Bronzies playing against other Bronzies.

Case in point: I used to have a reasonably greedy 2rax-expand build.  I still bring it out every once in a while.  But because Siege Tanks got buffed in HotS (I'd call no longer needing to research siege tech a "buff"), I now find it far more worthwhile to go rax, bunker/factory, and then set up a bunker/tank line in front of my expansion.  It's slower than the 2rax build, but...

(By the way, never do this without scouting, because it's bloody useless against Banshees, DTs, etc...)

When your opponent isn't playing super-greedy but you are, he's going to have a window of opportunity to stomp you flat. By way of example: let's say that you're doing a 2rax expand, whereas he's going to just run 3rax and a factory off of one base.  By the time you have that expansion up and running, he's going to be plopping down siege tanks right outside, and you're not going to have the forces to deal with it.  Obviously playing greedy is going to give you a massive advantage in the mid-game, but that depends on you surviving to the mid-game.

This is all pretty basic stuff.  I'm not expecting to win any awards for insightfulness here.  My only real question is why Bronzies don't play as super-greedy as the pros do, and I think the answer has to do with confidence.

Back in the Brood War days I'd play against the computer and routinely have my ass handed to me.  The reason being I expected a very early attack and would thus sacrifice a strong economy to get units out as fast as possible.  Anybody who 6pools today can tell you that it's a make-or-break thing; there's no coming back once you cripple your own economy for the sake of having very early units.

Bronzies, I think, operate under the same logic as I did.  I'm deathly afraid of my opponent, so I'm going to get units out as quickly as possible.  Not cheese, mind you, but they will sacrifice a stronger mid-game economy for more early firepower.

Another reason why Bronzies are more likely to do this sort of thing is because that's what the computer does.  If you play against the AI, it will punish you for being greedy, (and the AI is capable of at least double their APM, even if they're playing at the same level) so they get it ingrained in their head that they shouldn't do it.

Then the joke is: the easiest way to beat the AI is to let it attack you, wipe it out, and counter-attack.  So you get two Bronzies play very defensive, cautious games, each expecting the other to attack first. Either could play greedy, since their opponent is bunkering up, but both are too afraid to.