I'm pretty sure there's only one message you get when you get permanently banned, which is the one you quoted.  It should do the trick, since there are really only two reasons why a member would get permabanned: spamming and plagiarism.  Ban evasion is a third, but I'm not sure whether there should be a separate message for that or not, since anyone receiving the standard message when they're using an alt of a banned account should know what they did.

Why not?  It seems like I'm writing this a lot lately: Theymos just isn't adding new features/improvements to the forum lately.  As far as members asking why they got banned, I think that's a load of crap.  99% of the time they really know why, but they play the babe-in-the-woods card in their ban appeal threads more often than not.  If they didn't start off those threads pretending to wonder why in the world they got that ban message, the rest of their post wouldn't contain much of an argument for their reinstatement.

So yeah, it'd be ideal if there were different messages for each ban reason, but realistically I don't think that's going to happen.