IMHO
If you are only flying from one 4,000' runway to another 4,000' runway in something that has a 1,000' ground roll, you probably don't "need" anything more than ASI. Now if you are pushing that same plane to its limits and putting her down on a 1,200' sandbar, you might want, "need" an AOA. I've been playing around getting to know my 182s STOL potential and true capabilities up at 3,000agl. I've found that my stall horn starts blowing about 25kts before the nose drops. I get almost no buffeting and the controls never feel "mushy" until just as the nose drops (around 35kts indicated) . That's obviously with no ground effect. So.. at those very slow speeds I only have my ASI (which isn't very accurate at that high of pitch) and my stall horn that's been blaring in my ear for the last few min as my air speed drops another 25kts. I'm just figuring out my STOL capabilities in my plane more for fun than anything else. I don't plan on landing on a 800' gravel bar any time soon, so I probably wont get an AOA but I can sure see how it would be nice to have.