For me it is life moving forward. Family, work, daily chores, now small child. all of that leaves me with very little time for myself. And that very little time I would rather invest in drawing a map, than browsing forum, because let's face it... reading stuff here is not very productive (unless we want to learn from each other)

I still occasionally look through some threads, but not very often. I do try to post every map in Finished map section though!
The other thing that personally affected my activity here was... well to put it mildly a slightly bellicose approach of some people in my threads.
I had felt back then that the spirit of guildsman here is somehow gone.

The other thing is that the world is ever changing and everything in it is too. Stagnation is a straight way to death.
I once suggested that the forum (as beautiful as it is) would gain a momentum with some updates and redesign.
I don't remember, was it Redrobes or other admin that said it would require a lot of work to even update vBulletin, not mentioning a total redesign.
There are much more responsive with better functionality and art dedicated forums out there. I am afraid that the forum will be slowly forgotten little by little every year if nothing will change here.
I understand that requires work and most likely money, so I am not judging. It's a mere objective observation.

That being said, people are coming and going. It is a natural flow. There may be an influx of young blood yet to invigorate the Guild. I do hope so.