It always feels sad to use up all my rerolls and still end up with useless cornerstones.
The queen should pay for my emotional loss.
Less amber than that but good idea I think, should be consolation prize feeling (2 amber is my opinion)
Many cornerstones produces about 10 amber per year.
A one-time 10 amber isn't a big deal.
Also, it provides some interesting options: skipping a cornerstone to purchase an important upgrade from the trader, or to pay the queen's land tax.
A smaller value can't afford any of them.