I do think the majority of exes are basically people you respect, who share mutual interests (and often social circles) and whose company you enjoy - but when you gave it a shot you found that you wanted different things out of life or couldn't stand their domestic habits or didn't want to be around them all the time. So once the dust settles from the split, if you still share friends and still see them around naturally, you end up on friendly terms again.
I agree with this. I never had a major break-up in the sense of arguments. I'm still in touch with my first kiss because we have family friends and so on in common, and contact is likely to be, "I think you'd enjoy this radio programme, if you haven't heard it," things like that. We don't meet at all often these days, as he's in NZ, but we would if we happened to be in the same country (he comes back once in a while to see his sister.)
Another, it was our early 20s and we just ended up taking different paths, but we chat quite often and meet two or three times a year. I get on well with his partner. While I once thought we would have ended up married, I can't imagine that at all now we're in our 50s. But it's still good to chat to him.
And the last, it was a long distance relationship and I realised that I was the one making most of the effort. We never broke up as such, we just never arranged another flight, when previously they had been very regular. But we still keep each other updated with life in general every few months.
Others, we kept in touch a bit and then you get to a point where you realise you haven't spoken for over a year - it just died an organic death. But if they pinged me on FB or we met in the street or something, I'd be fine with a catch up.
Basically, the men I've been out with over the years haven't been bastards. I have also spent a lot of time single in between, so i don't think lingering feelings interrupted the next relationship. I have friends whose exes are complete gits, but they have to be in contact because of the kids, but definitely wouldn't be otherwise. And I also know people who aren't in touch with people they knew at school, uni, previous workplaces, whereas I am, so it's probably partly a personality type of thing.
But then a former fiancee of my father's came to his funeral, so maybe it also depends on the patterns you're brought up with.