That's the way I see it with the risk being the higher the sought after power from the runes, the greater the DC but also the greater the chance one gets hit with a failure/complication etc.
For the more Trad GM who aren't fans of these runes because of the fictional manipulation it provides players, they may find they could work in planes or domains with concentrated chaos, desire or luck - where the runes may take the function the PC desires or least desires due to the particular setting/location.
One more time. It has nothing to do with the players having ability to manipulate the fiction, I have the same issue if the GM manipulates the fiction in a similar fashion. The players make dramatic changes in my campaigns, it's just through their characters and what the player decide to pursue. Meanwhile as DM once I establish fiction, I stick with it (unless of course I royally f*** up but that's a separate issue), even if the characters breeze through what I thought was a significant challenge.
It's really just a question of approach and preferences. From a gamist perspective if there's some sort of balance to the ability to make a declaration like the runes there's not really an issue. Different games have different approaches. Except I don't want to play a game where the player makes decisions about the world that has significant impact outside of what their character does. On the GM side, the GM should establish the fictional state before play starts even if the exact details of the interaction of character and the fiction is largely improvised. If there are ancient runes, the GM should know what they mean before the characters see them and they should make sense from the perspective of the NPC that created them long ago.
Having that fiction change on the fly with changes from anyone at the table makes the fiction about as solid as pudding to me and it makes it less enjoyable. If it doesn't matter to you that's fine. We don't have to see eye to eye. This repeated insistence that it doesn't matter is what gets tiresome. It doesn't matter to you, it does matter to me.