We have known for months that there were no group dungeons come with Morrowind so why is it a big surprise? Group dungeons will come in a dlc 3rd quarter of the year.
Sounds like you're surprised and regretting your purchase.
It's quite important that folks read announcement and update info as they tell us what the planned content will be in advance so you know what to expect before you buy.
Most of us knew months ago what the content was going to be which included a new trial and 2 public dungeons so there was ample opportunity to find out and mull it over..