grenv: Not to mention it wastes my opponents time

Lol, indeed not to mention it. Given that they get pleasure from the final move, it wouldn't be a waste of their time, it would be time well spent! It's a waste of your time because you derive no pleasure from indulging them. Indeed, it would seem that you fail to recognise their pleasure at all.

I'll be as polite as you like

If you knowingly resign when your opponent would like to finish then you're not being as polite as they'd like. In fact, to those for whom it's important enough to block a resigner, adding a FU smiley to the resignation move may not make that much difference!

Of course, to you, deriving pleasure from moving the last piece off is ridiculous enough, so people who value it that strongly can only be ridiculous squared in your eyes, and thus deserve all disrespect due them, right?

In fact it's boorish and impolite in my opinion to keep going,

If someone doesn't care either way and knows that you're impatient to move on but deliberately plays on just to spite you (and not for some other reason like not really understand the resigning system or being sure that they can trust it) then, I'd agree, they'd be the ones being rude to you. Of course most times it'll be because people aren't aware of your preference or didn't think in time before they hit roll. Resigning is a more deliberate action so it's perhaps less likely to be done accidentally/unthinkingly.

to demand that others keep going in order to satisfy your own ridiculous need

There's a difference between someone expressing their preference and you denying them that pleasure, and someone demanding it. Making demands is rude but surely a knowing denial is rude, too?

Kind of like needing to have the last word... :)

Maybe. It depends on what need it serves. Getting the last word is probably** more a competitive thing wanting to take the last piece off is probably more a completion thing. Like putting the final piece in a jigsaw before breaking it up and putting it in the box, it's logically unnecessary but it has a tangible psychological value.

**I say "probably competitive" with regard to getting te last word because I've played people who like to get the last word because it feels rude to them not to respond. With two such people they can go on doing smileys at each other for ages! Eventually one gets up enough courage to be "rude".