I don't think the AD was really a consideration here, but rather, the ability to choose a reward for actual use. Someone who actually wants to USE a GE reward I think will appreciate being able to pick what they want, rather than having to roll the dice hoping that they win it. It may be a nerf to AD returns, but since we're only throwing in stuff that we ourselves consider to be junk, I don't think Inno really cares about that, much like we don't really care about losing the items that we throw into it.
Well I mean I think the actual consideration was reducing the amount of fountains of youth accessible
But yes, if your new city wants some level 2 Terrace Farms this is much more reliable than it was (my last new city took close to 3 months to get its first level 2 terrace farm because while it got the upgrade the first week it didn't get a base for it for a long time; now it's somewhat reliably every few weeks and there's no danger of an upgrade without a base).
At the same time though GE5 shows the issue with how far they leaned into fragments. You have nothing to show for it at all until at least 4 full clears. And most of the items not til the 5th. This creates a substantial lack of excitement if it's testing your limits that "what, you mean before I get *anything* from this I need to do it again 3 more times?".
For the highest value prizes that makes sense - the forgotten temple and feathered serpent statue can't be made too common and if they're going to be rare it's kinda better that they're reliable.
But for some of them that I'm not even sure I want to build when I get them, surely they could let us get "too many" of them before we don't care if we get *any* of them (looking at you greater ritual flame, divine sky watch, and chain attachments for the serpent) by having 1 of the chests offer a full one at random that might not be what you want, but is something to show for your effort if you can't handle doing GE5 every week.
Fragments are a nice tool in their belt, and sometimes they make good sense for the reasons you espoused. But sometimes a bit of RNG that's on average more rewarding but less reliable is a good thing to mix in too!