I joined a fellowship because it makes progressing in the game so much easier!
- No trader fee to deal with, and always at least a few people having trades up means it takes far less time to get all the goods you need to research/build/cater provinces at something beyond the pace of a 'legless, blind, backwards zombie sloth'.
- (in an active fellowship) Lots of daily help, either with polishing culture buildings to keep your bonuses up to help produce more supplies, builder motivations to make upgrading a bit quicker, and/or a steady flow of coins into your main hall.
- Tournaments for raking in those relics and extra KP's, runeshards, etc... especially on your boosted weeks, having a fellowship that can consistently make the 4th chest is great! Who doesn't want an extra 9! more of their boosted relics?!
On the chat side of things, I think a lot has to do with just how busy people get IRL... Right now coming into the summer time, when people take more vacations, spend more time outside, etc... it seems like there's little in-game chatting going on.
But in the winter, when only insane people like we Canucks dare to brave the howling blizzards & sub polar temps, people seem chattier as they stick indoors where it's warm!;P