I will apply then because they are free but pretty much every time I've used one there were standard suites available at checkin so I would have gotten upgraded anyway. So what's the point?

Part of it is that I almost never care whether I get a suite or not. There are a few times when it's nice but most of my travel is solo so rooms are usually fine. I would rather get more points (which contributes to more free nights) than get an upgrade on a room that I already have. I've turned down a $50/night upgrade from a room to a premium suite; that should give an idea of your much I value it.