Yeah, I don't see the fuss about M+KB
Moving the camera in a direction your character is not facing while playing with no lock on AND having fine control over the direction of your weapon simply works better with twin sticks. Playing with KB
is not impossible, there's nothing impossible when people have beaten dark souls with stuff like drum kit controllers.
But just because something is possible doesn't mean it's optimal. Unless you're absolutely averse to twin analog sticks pads there's really no reason not to use such.
How viable is it to go full tank and not roll in DS2? I know its doable in DS1, as poise and armor actually does something in that game.
Poise is not broken in DS2 at all. It is just more balanced than in DS1, and of all the souls, it's the soul game with the highest variety of viable build. Almost anything you can think of is viable in this game, bar using magic or split damage weapons in DLCs because the DLC bosses have inflated defenses. Technically it's possible to kill something like the fume with sorcery, but why would you? it's like hitting a hard wall with your bare naked fists.
Poise in DS2 is not active at all time but it is active when you are using your weapon - hyper armor mode -, meaning that you need to be consciously trading hits, rather than getting hit and r1ing after the fact. Heavy weapons have a lot of hyper armor, use stuff like greatswords, ultra greatswords, maces and so on. Don't expect to trade hits using something like a dinky dagger or a katana.
The way poise works in DS2 thus both requires active player thinking and specialization in build : you don't get to put on some havel or stone armor on a dex character and expect to r1 spam some bosses like you can do with 4 kings and nito in DS1, you need a true turtle build with high STR and the right weapons. Greatshield work fine too, any with high stability will tank pretty much anything in the game without eating your stamina. It's like an integrated in-game-world difficulty setting where putting a greatshield on a character trivializes all of it. If something does some environmental or elemental damage like Smelter you can still turtle after eating some gems up.
DS2 is my most played souls game, I've done a run with pretty much every type of character, the only gripe I have with it is going with a dex character and dealing with the constantly breaking weapons with their insanely low durability. But that's just a minor gripe compared to how many builds aren't viable in DS3.