Hi there,
I never played Morrowind, but in TES Daggerfall, there were tons of holidays which enhanced the game's culture and gave benefits peculiar to that holiday. For example, on one holiday (I don't remember which) Temples gave discounts to people for their services. It's been so long since I played Daggerfall that I don't remember if the holidays were global or regional, either. But the staff of ESO has access to all of it -- and why not? When there's a holiday in Tamriel, have some sort of festival in cities like Stonefalls or Daggerfall, and give some benefit, like on that day the 250 gold boon at the stables is free, or in another the Enchanters give discounts on their wares, etc.
It would greatly enhance game culture by describing the holidays and their significance, and the little benefits would quite certainly be loved by the gamers. What could be cooler than the occasional festival, with decorations sprouting on the merchant stalls and dancers in the streets? Probably wouldn't be super-hard to code or implement, either.
Thank you for reading my idea.