I play on artemis, and even though it is the most populated, there are a number of zones that are empty. Overall, the game population does seem slightly less from when I started back in mid chapter 3. There was an increase with chapter 4, then population dropped down, then a slight increase with chapter 5, and then more population decrease.
The starting zones, howling mountains for humans, elven island for elves, and shadowforge for dwarfs usually have a couple new players, a lot of alts/mules, a few high level players in logar, and a few gold spammers. Most ppl are concentrated in varanas, the kingdom of rarozan(high lvl zone), and still doing RT runs(even though RT IS OBSOLETE).