Note also that until we see DAI, we won't know the long term consequences of actions like putting Bhelan on the throne of Orzammar (as many do), even though he is a despot of the highest order. It also remains to be seen what the long term effects of performing the Dark Ritual with Morrigan were (again, as many people do, simply to save their Warden's skin). And what about killing Flemeth on Morrigan's say so (again, something which polls suggest most people do, for the loot and EXP if nothing else!) If Flemeth turns to be instrumental in helping save the world in DA:I, then the world is going to owe Hawke a pretty big thank you for correcting the Warden's blunder.
I'd like to see how many people admit they werw wrong with these choices, if any of them do end up causing disaster in DA:I. Or will they do what I suspect they'll do - quietly go back to the Dragon Age Keep, create a world state where they didn't make these mistakes and then claim they always knew that those other choices were wrong.
Judging either character on what happens in the future is pointless. As Varric's story makes clear, Hawke made the decisions he thought was best, and they stand by them. Cassandra wasn't there, so she doesn't know what the pressures were or the realities were. Good, bad or otherwise, their decisions and motives are now on record, and if people don't like it, then that's just tough - because they did all they could, and frankly more than anyone had a right to expect them to. Kirkwall heaps a lot of injustice on Hawke's shoulders, with the fate of his/her siblings and mother etc. It would have served some people in the city right if Hawke had just said 'Sod the lot of you' and left them to burn in any of the dozens and dozerns of deadly crises that arise. But instead, Hawke helps out - what more did people want?!