Obviously. But if you disagree, you're perfectly free to decline.
Yes, but that misses the point. You were talking about why you think it's perfectly fine to ask if you're offering a better seat. That's your rationalization for asking. If I don't think it's a better seat, then, in my mind, there was no justification for asking, and you've interrupted me.
Personally, I don't care if someone asks PROVIDED it's before I'm settled in and have gotten out my music player and put on my headphones, which I do
immediately upon taking my seat. If it's after, you've disturbed me and you'd better have a darn good reason for doing so (meaning a reason that
I think is darn good).
However, I also have no problem saying, "Sorry, no," to someone who asks me a favor I don't want provide. However, a lot of people do and, at least in my experience, more times than not, the askee starts an argument or, at best, starts whining, "What am I supposed to do?" Those are interactions which I prefer to avoid at all cost.
I'm not saying you do this, and I'm sure you are gracious in accepting a, "Sorry, no," answer but, again, in my experience, that puts you in the minority.