Between the changes to Prae and the other old dungeons, a brand new and very popular PVP mode, not to mention the changes to the rest of PVP in general, and the most mechanically heavy Ultimate in the games history. 6.1 is in fact one of the biggest patches in terms of new content to do in the games history.

Thats also not counting having a noticeably longer MSQ then normal for a .1 Patch, or the Tataru and Omega quests getting added later.

This is actually the biggest .1 Patch we have had in a longggggg time, like sense 2.1