I'm not too worried about the picture of the mage, but I do like pictures of the spells.
The mage ability card does have a bit more info that's sometimes handy to check against - but mostly more as a new player. I can imagine that it won't be long before I know them and the abilities well enough I don't have to check - I'm thinking of things like how often can I remove conditions with the Priestess, vs a purify spell etc.
At the same time, this could be captured by text as easy (or better?) than the card image?
I thought I'd refer to the school types etc more than I do. In the end I just add cards that look interesting and swap them out when I see their cost, rather than looking for spells by school.
Quick question for those who used the old SBB, is it necessary for the spellbook builder to show a picture of the Mage and allow you to view their ability card? Or can this be dropped?