For example, for the Priests upgrade, if I pay 800 gold off of it then the next person who comes to the Citadel can see thats theres only 1000 gold left to pay. They can chose to buy a different upgrade or buy an item just like normal, but if they want to they can pay the 1000 gold thats left and get the Priests upgrade. It's still their choice, and no one can force them.
This is a dumbing down of the good mechanic already in place. It would allow people to upgrade their DG and the citadel without having to make a choice. Choices are a good thing, they vary the game separating good players from bad ones.
Peoples teams lack of citadel upgrades is usually not because of game mechanics preventing them, its because of their team. If your team is bad, you will not get many citadel upgrades and you may lose for it. My personal buy order is:
1. monks
2. vlemish faceguard
3. currency I
4. one of the armour's and boots of speed
5. priests, angels (co-ordinate with ally who buys catas)
6. mageslayer
7. giants (or ally buys giants)
this buy order is from a 2v2; we are yet to lose one. It would undeniably easier to get the citadel upgrades in larger games.
Arguing against a core gameplay mechanic like this is like demanding valve introduces aimbots into cs for players who have bad aim or are forced to play on a laptop. Not only is it silly, it removes an element of skill from the game.