I know a couple of claustrophobic people. It "doesn't matter" because they wouldn't be caught dead in such a location. If it's OK not to have these people on planes (and maybe when everything is accounted it is OK), you're right.
If they're claustrophobic enough to the point where they can't even be in that position, then how can they handle a plane as it stands, even with windows? It's not like you can break the window in case of emergencies, and if anything, it's reinforcing the fact that you're 30k feet in the air in a tiny sealed box.
I'm not claustrophobic, so I can't explain exactly, but I think the evidence of altitude actually counteracts this effect, rather than compounding it as you suggest. In general, we wouldn't expect psychological maladies to present in reasonable ways.