I just finished playing Infamous: Second Son and what struck me was how short it was. That doesn't mean it lacked things to do, just that unlike some open-world games, getting 100% completion in each section wasn't a requirement in order to progress.
The ending did seem to come a little suddenly but at the same time, there wasn't a lot of padding to this game: things were very stripped down and after each story beat, the game was open to the next one. Players could design their own story to an extent-how liberated would the city of Seattle become? How much dirt could you dig up on the DUP (the bureaucratic enemy in the game)? Did you want to dig up the hidden informants? And so on.
What I liked about this was that it felt really forgiving: not all players can master all skills well and some people just don't have the time to dedicate to that mastery. So being able to pick and choose missions I enjoyed over ones I didn't, while still allowing for progression was really nice. The last experience I had like that was with Prototype, many years ago.
But in an open world game, the option to proceed and add to my own story, instead of running around doing whatever grindy shit was required of me (looking at you, Grand Theft Auto 4) that didn't involve running a criminal enterprise (send email!) felt like a rather welcome relief.
It occurs to me to contrast this experience with Batman: Arkham Knight. This is a game that kept the ending from you until you completed all 250-ish Riddler 'tasks'. These ranged from interesting mental puzzles to (for me) grueling timing tests to race tracks with death traps on them, to breaking random, unrelated containers for no storyline reason.
I never got the ending to that game because fuck that shit. While I enjoyed most of Arkham Knight, gating the ending behind such penny-ante tasks is really, really dumb.