The majority of the paltry repair cost is either through A) Completing dungeons or B) Wiping in raids.

Sure there -are- ways outside there for gear to degrade, but never to such an extent where it's an active concern. Removing repair would have almost no impact on the game's current economy. You already get gil in excess of the cost just by doing a daily dungeon.

Collectibles from crafting and gathering reward disproportionately more than it takes.

The point being here is that repairing is already so little a cost that you can remove it to no detriment at all, but for the sake of 'inflation' you can just cut it out of the dungeon reward. Literally just there.

If you want more gil sinks, fine, but don't pretend like repair costs are somehow holding the line against inflation in any capacity.

They are so close to being a non-factor that it would legitimately surprise me if they -were- a factor for anyone, and not just something you do on routine after coming out of a dungeon.