Some I do, some not. For example my carry 320 is normal, but the one next to the bed has raised sights on it.
Are they necessary... I don't think so. You should be able to hit steel at 25 yards no problem without them. If you can't, it's more a training issue than the sight being obscured.
If you're going to 75 or 100 yards, I think they help some.... but that's not an easy shot anyways, and not really what a pistol is designed for.