Well, no matter how you look at it, masterminds definitely have the fewest primaries by a wide margin.
Yes, pet customization is long overdue.
There was a suggestion in someone else’s thread, allowing masterminds to custom choose their primary attacks as well… separate from which pets they were using.
I don’t think the actual way they suggested doing it would work, but that would be a way to increase the variety of masterminds without having to build a new pet set. You could have the special effect (minus regen for bots, plus crit for ninjas, etc.) be baked in depending on pet set while allowing for more personal attack variety.