I don't characterize the clearance "negotiations" you hear as disagreement or antagonism. As pilots, we all love it when controllers have a good plan and execute it. When controllers can't give us what we ask for or when they want more info about why we're making a request., it's usually because it's not in their plan and it can be a big chore to amend their plan or to phone the next sector and ask them to amend theirs. There's usually a reason for everything.
I think usually controllers are friendly, accommodating people who really want to make pilots' lives easier. I recall flying back from Nantucket one busy afternoon and a Mooney asked to overfly the city of Boston at 3,000 feet for sightseeing. I thought to myself, "boy is he gonna get it." But the controller asked him to standby... checked with the next approach sector... and said, "Can you make it 6,500 feet?" Everyone wins.