The X-Men are all about change, but that doesn't mean that some changes aren't bigger than the others. The '90s were a time of seismic changes for the comic industry, not all of them good, and the X-Men weathered these changes as the stars of the biggest comics of the decade. The beginning of the 21st century would see Marvel have a massive change as well, as writer/artist Joe Quesada took over the company as editor-in-chief. Quesada wanted to fix Marvel and started at the top.
Source：https://www.cbr.com/the-x-men-in-the-00s-part-one-epic-and-tragic-times/
