If I want to have no life and play only in Kaesora, I shouldn't be punished. I've said this in threads similar to this in the past. Citadel was a much much much more popular zone before exp nerfs and item drop rate nerfs. Now people go there if they need things other then exp. Instrument of Disempowerment, Tome 2 (rarely), Claw Commander, etc. It's not because it's a good zone anymore, but necessary. Or last resort if BQ and Kaesora are already occupied. The reward for switching zones constantly pales in comparison to the -10% and -25% duration for remaining in a zone. Not to mention minimum, 10 minutes between zones with people in tow.
TL;DR- Remove the "rewarding" exp bonus system entirely. Give all zones a flat small % exp modifier boost, and tune exp to zone difficulty. Make harder zones give good exp/ loot again.