I've played all 3 races before by picking, and by now playing random, and I can say first hand while there is whining about each race, nothing has come close to what I've experienced with random. The number of people that I've been civil with on ladder in the past now tell me to kill myself, die from cancer, hope I get AIDS, or the most recent amusing one from x6Perfect was "go fuck your own mother's loose vagina you stupid fucking random player" whatever... of course, none of it matters really I don't take it personally and can even get a laugh from it.
But it's nearing 50% of my games I have to deal with some nonsense bullshit now. What really ticks me the most though is the perception Random players are cheesers. I can only say this is the furthest from the truth from what I've experienced. I don't think I've experienced a random person "cheese" in almost any encounter, EVER. It's extremely rare. However, if you count my last 40 games, about 25 have been early game allins/cheeses by the opposing player. The last 9 games in a row were all cheese, not a single macro game. It's become so ungodly frustrating playing this style. Looking at my match history, I just encountered an allin baneling bust from ~20ish drones that I lost to, a 14/14 baneling bust, a 4gate, another 4gate, a 1 base 3gate into dt rush (pvt), a 2base allin baneling bust, a speedling allin, another 4gate, another 4gate, and then FINALLY a macro game from a terran player...
So you might say, why not blindly prepare against them? I try. I really do. What's ironic is that I start to prepare for them by pumping out early troops (say extra speedlings in ZvP), and then if they try to expand, I'm screamed at for it (putting on pressure with lings).
Yes, this is a rant, no you don't have to tell me that allins are part of the game. I realize it. Understand this is just coming from a pissed off player who's lost to a shitton of allins today. I utilize allins myself, but to the degree I've experienced them in the past few weeks are driving my crazy.
tl;dr. Players who play Random rarely cheese. Players who play against Random cheese at an exponentially high level, if not simply because they feel they are at a BO disadvantage. Even if you think an allin is likely, if you haven't scouted it, you don't want to put yourself behind in a macro game by blindly preparing. Random is just so frustrating to play, even if you have a good grasp at all 3 races.
P.S. I'm high masters. A the start of the day my first four games were all vs people top 20 GM. Played LiquidRet twice yesterday when he was in his "cheese mode" (go figure), when I lost to him I got -13, when I won I only got +11, so that gives you a view on my MMR, since Ret is also high GM on NA.