Given how many points you need to invest into Memory to get a single slot I cannot see how any skill which costs more than 3 Memory will every be worthwhile. 4 Memory slots? That'll take the full attribute points from 4 levels, and one level means a lot in this game. Hello to fighting charged frogs at level 3, hello to fighting Void Salamanders at level 5.
Ten slots is 10 levels worth of points. Ten levels out of probably 20 or 30 at the most - so you'd better hope that you get incredibly lucky with the RNG drops because losing 10 levels worth of power into Memory will cripple you. A spell which takes 10 memory to cast shouldn't just kill one enemy on the screen in one shot, it shouldn't just kill everything on the screen in one shot, it should kill everything on the current map, and the next three maps.
Memory seems like it was intended to murder the mage classes. Especially odd given that two additional mage classes were picked as the users choice skill sets.
Skill crafting as presented is just the ability to craft new skills from skill books.
These new skills are preset....
So it is better to think of "Skill crafting" as access to 1-3 extra skills per skill tree and that is it.
Actually, the hope for skill crafting is that the game does the hard work for the developers - a system which smartly combines skills into appropriate combinations without the developers having to hand-craft animations for each one, because there would be way too many combos to do it by hand.