This isn't a suggestion, since at this point in time I don't see them adding more custom crafts. This is just like a what could have been kind of discussion. It's a shame they never decided to add more custom crafts to photon arts, or at the very least give every photon art a zero variant.
There's some photon arts that are rarely used since they have low damage, take too long to use to be useful, or are just pretty boring, so it's just a shame we didn't get the same treatment with photon arts as with techs, since every single standard tech (as in not compound techs or other special kinds) can be customized.
I know that a lot of weapons are also used by a scion/successor class, but that is not true for all of them, and that wouldn't really be the same thing anyway. Those classes use different photon arts anyway so it's a completely different thing. I also wish there were scion classes for every single kind of weapon in this game, since it not being the case is also a similar kind of missed potential.
I've just wondered why they never decided to make more customization for photon arts, and at this point in time with NGS coming next year, I don't really see it happening. I would be very happy if they did decide to do this, but this is pretty late in this game's life, and it's surprising the Luster class was even created at this point.
I just wanted to make an actual discussion on these forums that (hopefully) doesn't turn into an opinion war. And thought thinking about all this missed potential could do that.