I've watched both soaps on and off (I'm not from UK originally). I live in Manchester so I preferred Corrie, but once something happened there which annoyed me a lot so I dropped it (if you care to know, some years ago there were Polish workers in the factory and somebody called immigration on them, which was totally idiotic--Polish people couldn't be illegal if they wanted to!, maybe it's the writers, not viewers, who should "get a life" and check up on news occasionally, then they wouldn't make such ridiculous mistakes), I've watched it during the tram crash week and maybe two episodes since.
I settled on Eastenders as my boyfriend also likes to watch it and as you say, it's harmless escapism. Most of the characters on Corrie just annoy me, Sally, Gail, Maria is so stupid and whiney, Steve always sounds nervous when he speaks and don't get me started on Fiz. As for John, he couldn't scare a fly. I like the characters in EE better, which is the main thing for me. I don't know about the humour thing, I never found either of the soaps particularly funny and bad things happen in both (come on, half the people on Corrie work in a factory and never seem to progress anywhere, even I managed to get a decent job after coming here!).
Anyway, thinking about it now, London is a huge city, much larger than Manchester of course, people in larger city are less warmer and friendlier than in smaller ones, it's completely natural, I guess big city is quite cut throat and the attitude is different (generally, not just in this country.) That may be what makes them more serious, like you say.