No there's no pure bias towards cast time as, considering it seems attack speed is valid for the eyes, there's something for both types then? If it works like that currently, which, again, in my experience it doesn't.
Also main tip for compasses: swim faster, that's only reason I outdid others on those quests.
I can't rule out the possibility that this is a ping thing, but I would be very, very surprised if it were. It seems evident that collecting scales with cast speed, or at least something magey, in fact I always thought that was common knowledge throughout the game. If there is some other phenomenon at work then whatever it is, that also would need to be addressed. But Every time I see someone instantly collect a sphere, they are a mage. Perhaps we should test it together next Invasion?
As for the eyes, I haven't quite figured them out. They are immune for the first few hits, and sometimes that seems to go on way longer. I think it's about being inside them or something? either way, as I said I noticed recently you can just instantly grab them, I think through the interaction button but maybe that's just placebo on my part. either way, since you're talking about actually killing them to collect them, then obviously, cast speed and attack speed would confer an equal advantage. So there's not one easier thing for each attack type (and it wouldn't be balanced even if it were, since there are vastly more white spheres than scrying eyes).
It is quite possible the root cause of the sphere gathering speed is something other than cast speed and I just assumed incorrectly, but I'm nearly certain it's not ping. It's obviously responding to something skill/ stat, or gear related. Understand, I'm not seeing people run over, instantly pick up the sphere, and THEN stand still for 4 seconds, like they are simply out of sync. They walk up to the sphere, instantly grab it, then immediately move onto the next. *THEY* are experiencing faster collection. The channel skill that happens when collecting is, literally, faster for them than it is for me. And it seems to always be mages.
I have healers in my guild btw who have very high ping and yet they report they have the fast collection on arcane spheres. And I have melees who agree it is slow for them.
As I said perhaps we can test this at some point.
Edit: one of the mages in my guild who reports fast sphere collection has relatively low cast speed, so now I am thinking it is scaling with intelligence or something like that? I always heard it was cast speed hence my assumption, but I'm happy to reevaluate that. Whatever it is, I think it's fair for there to be a melee equivalent.