I'll guess this is one of the last remaining poker etiquette's still standing, and it is losing it's legs. Some poor sod is down to his last chance, and there is no need to pile insult on top of his injury.
It would depend I think on the size of the pot. Is it worth betting for? There are many times I might bet into a dry pot, usually to tell the other guy I got it covered, set, flush, whatever. I more often will check a small all inner with a 3rd or 4th hand in the pot, even if I think the pot will be mine.
Then there are those pesky, neat, bounty tourneys, where when somebody goes all in, there is something more than just the pot at stake. In those cases, it can be correct to eliminate the competition.