I think that the increasing unwillingness to "come across as argumentative" is actually fostering hypersensitivity and hostility. When most people encounter pushback or resistance, or even the appearance thereof, they will stop and moderate their approach and reactions; but when unopposed, they become indistinguishable from the mentally-unstable lunatics we fondly refer to as "Tumblrinas". They get bold, and then they do exactly what human beings almost invariably do and begin to feel entitled to absolute dominance.
I think that it is actually incumbent on people to present themselves as confident in their positions and willing to engage, and imply that they have, in fact, a rational basis for their opinions rather than just an emotional response. I think people respect that more, unless they're thin-skinned egotists who cannot brook dissent (in which case, if your boss is one of those, you're screwed no matter how much you impliedly grovel because you will eventually displease them).
Granted, sometimes a softer approach is called for, but in general, you undercut your own position in a discussion by a weak presentation. Respect can be shown by assuming the other person can handle the truth, after all.
...Now that I'm thinking about it, society's idea of "respect" is getting incredibly warped. But that's another discussion entirely.