I dunno, I always feel like the only reason Spinel is ever there in these things and CLAMP-PLA illusts is because he's a cute fluffy mascot (whether he liked it or not). It wasn't a matter of diversity, just cramming all the kawaii CLAMP things together. Spinel had almost the same role the globefish bouncing has in the Wonderland videos: just be there.

Now, Kakei and Saiga from Gohou Drug, I do consider variety because they're not cute or popular. Or Gingetsu with Ran in the background, even if you don't see their faces. Spinel? Not likely.

Now that I think about it, why on Earth is Doumeki even there, besides fanservice? Watanuki had both his own eyes, so Shizuka shouldn't be able to enter the shop yet... Waitaminute, why am I pulling canon logic on a crack crossover video?! *rolls eyes at herself*