I checked the Japanese forums and noticed Foxclon saying something in regards to the reason for the 20 spell limit and how Unbridled Knowledge came about.

Could we get a proper translation of the message?

Also I believe it was not addressed but is currently in discussion about Unbridled Knowledge's long recast. Currently all the spells tied to this job ability are mainly underpowered or broken. Wouldn't the recast make more sense if it was 2 minutes?
If not, the potency of these spells definitely need to be reexamined.