> But I think that's a pretty narrow use-case
Then you're not paying attention. It's a very common use case.
Did you ignore my pointing out that my family and my co-workers call me by different names? This is _very_ common.
> For teachers, sure, but I don't see a reason for teachers to be Facebook friends with students
I don't see a good reason for anyone to ever have a Facebook account at all. But many people clearly do, and Facebook is doing all it can to ensure that all real-life relationships are reflected in Facebook... but not actually making it possible to do that sanely. That's causing problems, and will continue to cause problems until either people realize that Facebook shouldn't be used for all their relationships or Facebook fixes their setup to work better or society in general radically changes how it's structured (and not for the better, in my opinion).
We can argue about which of these solutions is preferable, and which is more likely (I suspect the answers are different), but let's not pretend like the problem doesn't exist.
As for teachers being Facebook friends with their students, consider the situation in India, where Facebook is pushing for "internet access" that only includes Facebook. At which point, if you want to communicate with your students electronically at all, you have to do it through Facebook, since that's all they can do on the internet.
The situation in the US is not that bad, but again some teachers are using Facebook for their classroom communication (by choice). I agree this is a bad idea, obviously, for oh so many reasons.
> You can certainly be searchable by names in different character sets
It's not just searchability. It's also whether people seeing a message from you recognize who the message is from, say.
> why not just make separate Facebook profiles
You mean apart from this being explicitly against Facebooks's terms of service and the fact that they will shut down some or all of these profiles because they decide that the name on them isn't a real name?
Again, as I see it my options today are:
1) Lie about accepting the terms of service, deal with the fact that Facebook can arbitrarily shut down parts of my social interactions because it decides it doesn't like what some people call me.
2) Set up Facebook relationships in a radically different way from my real-world ones.
3) Just don't use Facebook for interacting with anyone I actually care about.
My personal choice is #3. Most people seem to choose some combination of #1 and #2, with a strong lean to #2. The EFF is claiming that this choice only has to be made because of some particular Facebook policies and users would be better off if those policies were changed so that the choice didn't need to be made (e.g. so that having separate Facebook profiles were actually an OK thing and not grounds for having all your Facebook profiles terminated).