What I think you're saying is that it might not be perfect on release, but that EA tend to patch a lot post-release, and that it may or may not therefore end up as a good game.
I'm not disagreeing with that. I'm saying that, if that's the case, I'd happily try it out (either free or at a reduced rate) on release, and stick with it while it was buggy. If the game is not good on release then I do not want to pay a 'good game' price for it on release.
Of course, given that EA tend not to release playable demos, tend to overhype every single game they release until you can't tell decent from awful, and tend to charge through the nose both on release and for 'content' released later on (which often inherently contain system/stability patches as well, locking out those early adopters who don't want to pay more for content), this is not a model that I am willing engage with.
So yes, I might play it. In a couple of years. When the price has dropped, and the two hundred 'new building' DLCs have all been released and are available in a bundle. Basically, I might buy it when I'm confident it's actually a full game rather than an elongated, costly demo and/or beta test.
Edit: actually, I may have misread, as you may be talking about improvements over the course of a series rather than over the course of patches. In which case I disagree. The Sims 3 frustrates me far more than the Sims 2 ever did, which was more frustrating than The Sims - primarily because of the increased pressure to buy micro-transaction DLCs for each game. My above points therefore stand. If EA follow the arc they're on, I very much doubt that SC5 will be anything like 'content complete' until at least a year or two after release.