I think the idea of 'creating a bigger alliance fleet' through 'donations' is against the rules as it is considered milking.

However, I did play several other games that had the alliance vault feature. Players could donate as much as they wanted and the resources could only be spent for alliance research such as WSA +5% for all members or some other tech, but with a lower increase than when a player researches a tech by himself.

If 2 alliances start a war, the winning alliance gets all the resources left in the losing alliance vault.

I'm not saying I'd like this to be implemented, though I'm not sure I'm against it either

I like the idea of donating resources and possibly rubies into an alliance vault,
Direct access to the resources/rubies by the members of the alliance is a dead end and it seems everyone has agreed on that.

So once we have the donated resources, what to do with them?

I like the idea of alliance bonuses