This is one of the reasons I've mostly stopped playing certain genres offline. I force myself not to play certain games. Some I know are going to suck me in for hours on end... and get me a meaningless piece of loot.
Sharing the experience online, especially with VOIP, makes these experience social though. And social activities are, to me, a good thing. I do not feel I have wasted away time if I'm bonding with someone else over that activity.
For offline, the game has to offer some challenge, or some form of "content". Strategy games, turn-based or RTS, with significant difficulty, make you think constantly and outdo yourself. That's another activity I consider worthwhile. Others train your reflexes... Certain grognard games have historical content that makes you realise what a lot of people went through in this or that war, so that's another reason I'd play offline.
RPGs typically have little of this, if played offline. Click click click click clickityclick. Minecraft and Terraria, or world-building games in general, give you an open world to exercise creativity, and that's OK offline, but definitely better when bonding over it with friends.
Nice to see someone who feels the same way about modern games!