I liked Skyfall, but Quantum of Solace was so terribly done that anything afterwards is a good sign. Skyfall quickly became a favorite of mine. You won't get any argument from me that the film was dreary, I think it was meant to feel that way, to feel insurmountable. Some of the scenes did drag on a bit. Not the best Bond film, but high on my list.
This isn't the first time I've heard the "M's Son" thing, but it may or may not be the first time I've seen the anagram. Honestly, I don't feel that it adds much to the film. M isn't a character we know much about, and that's purposely so. She can pull of "steely" because we don't know much about her, and we're supposed to wonder what she's done in the past. After all, you shouldn't be the head of MI6 without some serious moral conundrums under your belt.
I think having this subplot be more prevalent would have trivialized the conflict slightly. It'd have gone from "Agent betrayed by Queen and Country, left to die in a chinese prison, returns to take his revenge against M, Bond, and Great Britain." (not a great logline, but good enough for my example). To: "M's highly trained son, escaped from a chinese prison, returns to take his revenge."
The storyline was very much focused on Silvio/M, but the B Plot of the NATO NOC list makes it an international conflict, something that could set back the entire world and be felt on a grand scale. This is more the tone of the Bond films overall. I'm not saying that by focusing more on that subplot the film would have suffered, but I don't know if it'd feel quite like a "Bond" film. It may be too emotionally heavy.
That said, two things sell in the movie industry: Sex and Bond.