Yeah, but he did all this arrogant an prideful stuff, he murdered indiscriminately, was responsible for a meth plague, was an evil human being, etc.
I think if the show ended in his downfall, with all his plans going awry it could have worked. I don't think Vince and Co. are incapable of writing a dark ending. Certainly, this is the "safe" ending, and probably the smartest choice. Why alienate the fan base by trying to be too clever or controversial?
In the end, Walt won. His enemies vanquished (Jesus... Mr. White -*gak*), loose ends tied up (HUELL!! (j/k)), family provided for (breakfast for life), Jesse alive (bitch!), Walt dies a free man (cancer would have got him sooner than later anyway).
The only "problem" is that this ending doesn't really provide for much discussion or interpretation, or "looking back" trying to piece together the clues. Once again, that's not a bad thing. It's just the show is "over" and it all ended kinda neatly.