Here is a great interview with Jeff Butler who was a producer for Everquest, Vanguard, and Everquest Next as well as many others at SOE.

Warning the video is 3 hours long and is full of great insights into the industry. If your just interested in Vanguard that starts around the hour and a half mark. The short of it is that their publisher Microsoft refused to give them the money they needed. As they thought that MMORPGS were small potatoes and only gave Sigil tens of millions when they needed hundreds of millions to make the game they wanted to make. Now by the time that WoW exploded proving the viability of the genera it was already far too late.

https://youtu.be/OTWdpXvxneQ