....respond to the question I actually asked: what the problem with having keys disappear after you use them?
Nothing, but what is apparently clear is that you have not played any Larian Studios games before? In all their games, keys did not disappear after use, you simply got rid of them.
But hey, there is always a first.
And I have no intention of using mods.
And that is a personal choice, just like using backpacks to sort your inventory and prevent it from being a clutter, yeah?
Why you think Larian placed as many free to take backpacks as they did within and around Druid's Grove, in fact, throughout most of EA Act 1? Just saying.