Lets not generalize
While it may not have been perfect for you, others did have a great time running it on those devices. The problem MS faced and is still facing, is that they can't seem to provide an equal experience for everyone. Take the flagship 950's for example; some have complained, others are just living with the bugs and some have claimed very good experiences.
Of course there will always be those that tend to complain and whine, but in this case, after experiencing the bugs myself, some of those complaints seem to be valid.
The reason MS gave "there were too many complaints" might actually be the reason, or it might just be a cover
Like I said the 950 users complained as well/the 730 users complained as well/the 830 users complained as well (some have started to complain recently lol) but these "older" devices were still allowed to upgrade. So I will continue to say that it was less about the complaining and more about the fact that they can't guarantee a flawless experience for everyone.
I don't mind the move
held on to my 920 thinking that it would get w10.. probably should've bought sth else