Skill books implementation for rare skills are OK.
But those lvl 1 starting skills not being available is bad implementation.
You can literally lose a skill from re-spec.
There's no excusing this. And those defending it is just ignorant of the consequences.
Sorry, itemizing skill with random vendor is not the way to go.

And please, assign a different item graphic for each skill book.
Don't be lazy and force the player to mouse-over every identical looking skill book just to check what they are.

[Linked Image]

Senses are pretty common. Everyone can tell one glance that each skill icon is different from one look. But put those Fire books next to each other, and you can't even tell what they are. Wasting more player's time with mouse-overs.