It has nothing to do with "like" and everything to do with objective flaws of the film. Indeed, I am quite pre-disposed to strongly like things having to do with dreams and did, in fact, "like" much of what Inception did while simultaneously acknowledging that it did it in a very shitty and unconvincing way, artistically speaking.
I never said that film shouldn't focus on the main character; I said that a film SHOULD work to develop its side characters, a heist film especially, and provided an example of a heist film that does JUST THAT and is the better for it (and far better than Inception). The thing about a heist film is that it can't be just about the heist, or else it's just a giant breakfast machine: a big set-up to what can only be a disappointing punchline; the trick to a heist film is to make us actually give a shit about the characters, to give each cog in the machine an emotional stake in the outcome besides basic monetary gain. Barring that, you're left with an all-style, no-substance piece of freshly polished plastic.
I will grant that Cobb is fleshed out, but even the writing of his character is not of any particular depth. He's given a basic goal and a fairly basic backstory, but we only learn of how his job makes him a distinctive person, rather than some particular personality quirk. It's like Plinkett's test in his Phantom Menace review: if a character is decently drawn, you should be able to say something about them other than their occupation or what they look like, and outside of "he was tortured and depressed," there's not much there for Leo's character. That's the movie's main problem: none of these people feel like real people; they wear nice suits and spout off one-liners, but outside of MAYBE Eames (and even that is due more to Tom Hardy's performance than any particular thing that Nolan did), there is nothing to differentiate the characters from one another, nothing to make them distinct and memorable. The performances of them are fine, but the actors are given nothing to work with.
And I will actually grant that there are SOME reality-based dreams (though even reality-based dreams feel 'off' upon waking, in my and many other experiences, because we DO accept unreality in dreams, which the movie acknowledges but then proceeds to ignore in favor of a rote realism), but to stick with that and, well, just that is to deny the whole fucking point of making it a dream sequence. If you want a world where the "rules" of the dream preclude the very possibility of exploiting the fact that it's a dream outside of the "tutorial" section where they do the folding city thing, that's fine, but don't act as if it doesn't toss aside a fair number of possibilities and render much of the movie's philosophy and cinematic pretensions obsolete.