Because sometimes things can get to a point where more is not necessarily a good thing.

What games do you feel dragged on for too long and could have been better if they got cropped a little (or possibly a lot)?

Phantom Pain. It should have ended after Skullface.

Far Cry 3. There's an unnecessary section after what I originally thought was/would be the end. I still haven't finished it because the last part just doesn't seem necessary.

Doom 3 could have been shorter. It's OK as it is, but it's actually a really long game for a shooter.

Alternatively, it should've been longer. It's obvious it was and is an imcomplete game. It would've worked better if it was either shorter, like you said, or if it had the missing content.

The main story for that isn't very long though.

Just about every turn-based JPRG not named Chrono Trigger.

the order 1886

Sim City. 

Wouldnt have minded a longer story if it was done better.  

Nier. I genuinely think its a seriously underrated game and one I like a lot, but it also felt like a 20-25 hour game stretched to 40 hours for no good reason.

I know this will a bit burn, but
Wind Waker
React, then read this: is there any necessity to travel the whole sea to collect the triforce shard's parts charts,then get it to Tingle to know that decrypthing costs 3k+ and go travelling again to getting all chart's treasures to get all that gold, then getting decrypthed and travel the whole sea again. Mind that there are 8 of this parts and each needs to be travelled to and made a little quest, btw did I mentioned that there is no story there at all, this makes that boring as f

Wasn't that part already shortened in the remaster though? I've never played the original version, but the triforce quest didn't feel long... just boring =P

Anyways, Wind Waker is a really short game imo, if anything it should've been longer (More dungeons specifically).