I actually (ab)use this feature. When you get too rich (above 50.000) your governors start developing bad vices. You can easily "spend" 30.000 (or more in a large empire) on queing buildings you're not really planning on building, thus taking you below the 50.000 mark.

If you need the cash later on simply remove the buildings from the que before building begins.

It's like you're putting the money in a bank to prevent your governors from getting lazy and decadent.