I've been on here/read the boards for several years and haven't found that people are particularly uncompassionate to each other (granted, I don't spend much time on AIBU.) You will get some people being nasty a few times on a thread, but it doesn't tend to be the majority of posts to a thread.
Are hugs still unmumsnetty?
YABU- hugs are still unmumsnetty
YANBU- we're not particularly nasty.
Admittedly the actual use of the word 'hugs' without the qualifier of 'unmumsnetty' is still uncommon.