Yeah I can defiantly see why that would be depressing. I doubt I'll be writing any programs anytime soon, i'm no programmer by any means, but I was in my pre calc class back then and wanted to text someone some kind of algebraic equation. Obviously this wasn't so easy to do since the only way to get all the mathematical symbols (as far as I knew then) was to copy and paste them from somewhere in the internet. So I thought about playing around with it, and making a keyboard just like the regular ones but with algebraic symbols instead of letters. There already is some pretty crappy version of that in the app store which I found later, and theres ikeyex in cydia which doesn't seem to work with the later OS versions, so I guess its still technically possible to make.
Anyway, I thought it was an interesting idea, but I doubt I will be doing it. If someone makes it well Ill gladly pay a few bucks for it, its useful for students, and since just about every student has an iPhone I think it would be pretty successful (except when it starts getting pirated that is heh).
You can just use a LaTeX typesetter. There are plenty within the JB community.