Agree, second, and applaud.

I've mostly thought of this as a matter of economy. To quote something I wrote quite a while ago, elsewhere:

In general, the things we don't like, don't want, won't tolerate vastly outnumber the things we do like, do want, do find acceptable. To enumerate them all would be a huge waste of time. And to name, for instance, only one thing we don't like - that is just getting started on the enumeration.

So, we communicate more efficiently by saying what we like, what we want, what we prefer, how we'd change things for the better, and so on.

Being rude is essentially being negative, with an additional effort to deliberately violate the conditions of felicity of whatever form of conversation is being used.

You could also cite (though I can't dig up a link right now) those studies recently published claiming that feeling rejected lowers people's IQ by a substantial amount.

Not an appropriate thing to do when you're trying to leverage collective intelligence; and if your aim isn't to leverage collective intelligence, why are you wasting your valuable time and talents posting on a public forum ?