Many people were long since tired of the old primals before blu was released, having farmed them for 5+ years for other reasons like mount, WT, helping friends, roulette, etc. To be made to grind them more than ever before for a close to zero chance of learning a spell when your starting point is already having grinded those fights more times than you should have to repeat anything in your life...

I don't think it's necessary for learn rates on those spells to be horrendous. Let people get them in a reasonable amount of time, and just let the carnival be the long term content part of blu rather than a torturous spell learning process.