Whilst I agree, I don't think that's QUITE the point people are making. Man Utd scouted well and made those as big signings. Granted, they've also had some duff signings, but the main argument for Man City isn't that you're buying the occasional big player and building your team around them like Utd have done, you're buying absolutely every big name player there is in a 'throw enough shit and some of it sticks' mentality.
Alot of Man City's big signings are already being cast out. Robinho (I know he's a stroppy git but still 30m you're more than happy to just write off), Santa Cruz, Jo, Given.. All of these were big money players that you're just not playing because the next big thing has come along. Even Adam Johnson who has played brilliantly and has the whole country talking about what a prospect he'd be now finds himself on the bench because Man City felt like going out and spunking 20m on David Silva.
Those big Man Utd signings you've listed have been used as the spine of their team for several seasons, yours are played until the manager and fans get bored of them and then are released or sold on with absolutely no care about making a loss on the investment.
I don't think that's a reflection of the club so much as Mark Hughes' insane spending policy. Half of his signings were complete stinkers that the fans weren't particularly impressed with. Mansour's policy has been to allow the manager to manage the team in all aspects, and that got us in trouble with Hughes. It's not that Hughes didn't scout his purchases so much as his judgment is extremely poor. It would be like judging Villa as a whole for the poor transfer policies of O'Neill.
Mancini is signing quality that he has wanted since his time at Inter, Silva being one of them. None of his signings are flops or wasted money. Adam Johnson and Silva play based on our opponent, and Johnson is less effective when we play the counter-attacking style. He will start against Juventus.
Men like Sheikh Mansour have extremely high demands. With the UEFA Fair Play rules, we have this year and the next to bring our revenue stream up dramatically. Those are the last years we can write off transfer fees as meaningless losses instead of amortize them. That, along with the 25-man rule, force us to discard players who can't contribute.
Be honest, if you had the chance to buy every "big name" player, would you? Of course. Real and Chelsea are the only ones who can compete with us financially, and they do exactly that.