There really does appear to be a disconnect between GB effects and GB age, from both players and the devs. Players expect high-age GBs to have powerful, generally game-changing effects. On the other hand, devs create GB effects as if they're all the same cost to obtain or possibly without considering cost at all. This is why we have things like Zeus providing the same military bonus in 6 squares as Aachen which takes up 24 and costs more to both build and level up (though on the player side, this is evidence of how certain bonuses will always be accepted regardless of the costs to obtain them).
As far as the Flying Island is concerned, there's a bit of a consensus that the effect itself is acceptable, but the numbers it puts out are lacking. Players want things like a higher shard rate, more FP, and the removal of certain rewards from the shards. Regarding the prizes players want to see removed, it's likely that the devs have them there for similar reasons as with other random prize pulls. Their philosophy is pretty clear in that there's always gotta be some bad/filler stuff in any selection of random prizes and that it can't all be top-shelf options. I believe this is why coins and supplies are a possibility from the common shards, much like how common relics in GE can give decorations. I don't really see that bit being changed here, assuming Inno changes anything at all. Maybe adding a secondary bonus or enabling shards to appear in outposts as well, both of which have already been suggested, would be enough here? There might be technical limitations with the shard mechanic that prevent this though. Could be the real reason why ToR only allows for relics to spawn, rather than the assumption that it's because relics are 'good enough' to not need a second bonus.
Anyway, it seems unlikely that anything will change. GBs rarely do. But is that a bad thing? It'll be a bummer for anyone hoping it gets made better, but it's still far enough away from the 'bad' tier of GBs that folks will build it. Probably about on par with something like the Seed Vault (which I personally feel is underrated, but I know it gets passed over because it lacks FP generation).