that I agree with, especially first and third. The second one, however, I believe is driven far more by both the type of narration (and presence of choice, even if in my opinion it is very, very illusory in SC2) and kind of stories one might enjoy...
I mean, you say that SC2 made more sense than being forced to assist Kerrigan in BW. I very much think it is due to stories.
SC1 and BW had the marvel of showing the perspective of showing different sides of conflict, which itself allow to tell a moreperspective based story, in a very similar way as... well... for lack of a better example, Watchmen, which is all about perspective and worldview (obviously for me, and due to diversity - and delving into backstories of characters to understand their motivations, goals and current mental state). SC and BW showed us what each side of conflict really is - and after prejudicing us from a different perspective beforehand and I enjoyed that a lot.
And there was a narrative reason for the game engine (kind of) limitation for decision making - firstly, player was a present character partaking in events, and those characters we all know - we did not get to immerse in them.
And also, showing that Kerrigan is willing to keep a pet cerebrate to fulfill her goals war character development in itself, and a great one, grim, but very lifelike, where things are rarely under one's full control (which later turned out to be the case with Kerrigan - and everyone at some point - as well). Far more than anything in entire SC2 in my eyes. For me, the characters in SC2 were charicatures of their old selves, as far as believability, writing, motivations and competence goes. SC1 and BW gave a solid grim grip on urgency and desperation of some actions, it presented Raynor's morals, various Protoss' devotion to their race (despite differing perspectives - remember Aldaris, the most fanatical of rescued Khalai, who was right all along, because he dared look past hope?) and so on, and so on.
And then I remember the anti-Dominion plot of SC2 with random encounters with protoss and sudden turn towards Starship Troopers, with incompetent Mengsk caricaturating himself of old times, hollywood drunk Raynor, a bunch of stereotypical supporting characters with no personalities or arcs at all and things about Kerrigan and zerg that in scope of SC1 and BW made no sense whatsoever (whereever have there been "artifacts" as the centre of Terran campaign? When has ever Zeratul used such a macguffin?).
I can understand preferring the type of narration and overall story of SC2, but saying it's made most sense kind of confuses me... ;)