Eeh as much as I agree with you regarding the illusion of choice .. Blu really doesn't need any carry to get his spells.
I finally decided to level it beyond 50 a few days ago and in one afternoon I completed all trials with parties full of BLU. At some point one party stuck together and we basically chained trials and raid boss.
So... It took me something like 5h to go from 30~ spells to all but the 3 last totem spell...

I'm not saying your wrong regarding meta or anything, but getting those spells takes hardly any time....