Originally Posted by Janju
[...]The problem is, before you didn't already find the book "Ice Blast" you don't know that it exists and after you find it, you probably have the wrong skills skilled for it.
[...]

There again I think it's more an "alpha thing" than a flaw that is here to remain.
Like, right now the accessible areas are full of "books", and I think it's safe to assume that, in the Divinity tradition, there'll be plenty of stuff to read, which will provide a lot of information about a wide array of things, like the pantheon, the source hunters order, and the 4 school of elementary magic among other things.
I mean, Cyseal, the starting village, has a library, it's probably there for a good reason.
So, which spell exists or not, that kind of information will be in the game, accessible to anyone willing to spend some time reading about it.
Another benefit of not having skill trees is that it's probably easier for devs to add "secret skills", that will not be required to complete the game, may be entirely superfluous in some cases, but are always a nice reward for those who find them.
Of course in our current age of walkthrough and guides quickly accessible on the internet such "secrets" lost a bit of their value but still that's the kind of addition that I like in games.