It's a feel thing for me. If there are a lot of people doing it and having a good time, get in there and do it as well (be a good sport). You don't have to do it every time but don't be that vulture that just sits there and doesn't contribute to the action environment. Gamble a little/show you are there to play.
On the other hand, if you are at a slow/nitty full ring table (and can't table change
) and no one is straddling I wouldn't either. However, one thing I like to do in these games especially if stacks are deep is try to and see if the table wants to do rounds of straddles with you. Deep stacks and rounds of straddles are a great way to get a slow game out of the muck. If you are a good player and can get the mandatory going it will do wonders for your winrate.
If you are at a boring table where people are unwilling to even do a round though I wouldn't make it a habit. Regularly putting in money blind with the worst position at the table full ring sucks if people aren't willing to give you the same action.