Sorry, but I'm still on the fence.

by Cody Miller , Music of the Spheres - Never Forgot, Tuesday, February 19, 2013, 00:32 (4295 days ago) @ narcogen

As for the rest... loot drops, crafting, and mandatory timed events that you can miss out on or will change your game world while you're not playing (Cody mentioned those)... have any of those things actually been in any way confirmed? Or are we just making stuff up?

Well, by definition a persistent world exists and changes when you aren't in it. So that means yes, you will miss stuff unless you play 24/7.