The thing is though that all of the schools are named as such because the spells that fall under them all share a common way of being used. Restoration spells all have the common trait of curing physical ailments. Destruction spells do the opposite. And so on. Mysticism is pure magic that deals purely with magic that doesn't affect the physical world in any conceivable way other than this: "the object was magically affected". Mysticism also dealt with more esoteric stuff such as souls and the very invocation of the gods, something that cannot be lumped into any other school. People have been saying that Mysticism is just the waste bin of the magic system, but thats because most everyone does not seem to want to understand WHY all the spells that fall under mysticism actually fall under it. And I outlined that in the original post.
So what. The other schools add a bit more to the teaching, whopedy do. It happens in real life all the time. Class teaches X subject, but maybe they no longer teach Y at the university. they never could get enough students for the class, so they incorporate the important parts into a related class.
Has to do with not only how magic works in TES, but also with general game mechanics. Magic in TES depends solely on how you put it to use, and as I said above, how you use your magic defines which school you are using. Yes, technically schools do not matter, but for the sake of gameplay it most certainly does. And this also has to do with the skillsets in general. The other skills are split up and rightfully so. That would be utterly [censored] to have one magic school and 14 other separate skills in the other specializations. Hence, magic schools as skills.
It has nothing to do with how magic works in TES. You seem to have a fundamental missunderstanding about this. It is how magic is taught in TES, not how it works. If we taught physics and chemistry in the same class called Chemics and that is how we always did it, the laws of the universe would not change. Science works how it works, how we understand it and teach it can and will change. And yes it is also a gameplay mechanic. One of which is better now that mysticism is gone.
Yes, there were. Read my posts, especially my first one.
No there isn't. No spell is inherently tied to any school. It is tied to magic and magic alone. This is explicit in the lore. The schools of magic are just teaching and classification methods.
No there isn't. Again magic is just magic, How it is taught is through the schools. Teaching both kangi, hiragana and katikana in a Japanese class doesn't make it less Japanese. If they choose to take spells out of mysticism and teach them in the restoration class nothing has gone wrong, you just learned things in a different way. No different than one person learning a language through their local community college and another person learning it at home with Rosetta stone, it is still language X, they just had different teaching methods to reach there.