Can you elaborate? Do you mean less space needed for the same amount of transactions or something directly depending?
Here is an article that should help you get started:
Segwit benefits.
Why should the miners impose limits or softlimits again? I don't see a reason for them for doing so. If you speak about propagation time and orphaned blocks athen there already are solutions to this with Matt's? network. That network even beats zero transaction blocks at the moment.
Why have they done so in the past? There is nothing that suggests that they wouldn't do so again.
Well, your last sentence is of somewhat psychological sneaky. Surely not everyone wants segwit. There are enough fears against it. It doesn't mean that they don't want more TPS. They might want it another way and that is completely legit.
No, it is not. It is just a logical statement. Once Segwit is implemented you have two options: 1) Use a client that supports it; 2) Use one that doesn't. If you opt for option two you are indirectly stating that you don't want the increased capacity or you don't need it.