My point isn't about game difficulty. I can beat normal AI easily enough. When I call myself a casual player, it is more that I play the game infrequently for this reason: never underestimate a player's ability to optimise the fun out of a game.
I like thinking of the aesthetics or of my settlement when placing buildings; I like being able to cinematically watch battles unfold. Instead, I am frantically laying down houses while also ensuring that every building is cranking out units like a Camino cloning facility.
Part of the reason that RTSs attract only the competitive scene is because games often cater to them specifically, truncating growth of new players.
Perhaps to clarify my position, I am not saying that this alone is the solution; probably the reason it flopped in Alpha 24 was due to repercussions that Seleucids mentioned. Some people have rightly noted that batch training does make operating a base easier, but it also makes each unit train faster of course. A major side-effect of this is an even more constant need to build houses especially as other production buildings come online. Population limit in theory isn't that bad of a feature, but the frequency of needing to build them as the game's pace racks up becomes annoying to say the least.