I seem to have a differing opinion here but I love long games if it is actually full of good content.
I don't play games with micro transactions and find a lot of open world games to be full of time wasters. If that's all it is then sure cut that out.
But with games costing $70 I would feel like I wasted my money for only a 10+ hour experience like some comments are wanting. That can be done in a single day. Assassin Creed games really aren't meant to be replayed either.
Games with lots of replayabilty are such good value and keep me entertained for hundreds or even thousands of hours. Games like Civilization, Persona 5, Zelda, Elder Scrolls, GTA, Metal Gear, old school Final Fantasy, Roller Coaster Tycoon, Xcom, Command and Conquer, Colonization, etc.
Maybe it's more a sign of modern games being full of stuff that isn't fun? Boring extremely limited NPC's, lots of wandering with nothing to do but collect some useless thing. In that case I agree with all the other comments but instead of wishing for a shorter game I would wish for a better game that is fun to play for long periods of time.
Shivs