Airplane wine glasses are the size of thimbles
 

i see this is many premium cabins. Why is this? More work for the FAs.

Not on DL. They are fine.
 

Best to do a private charter, I think. That will take care of your concern.

Often when it has become apparent to the flight attendant that the refills will be plentiful, they switch to a water glass!

Part of the reason may be that it's easier to "cut you off" if the glass size is smaller. If you become visibly intoxicated and still have half a large glass in your hand, and the FA tried to take it away, it would trigger a scene.

My thought is that smaller glasses are sturdier than larger glasses with delicate stems. Those glasses have to put up with a lot of abuse in an airplane and on the ground with the cleaning and shipping process. Plus, smaller glasses wouldn't take up as much space in the galley.

Wirelessly posted (Apple iPhone: Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_4 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10B350 Safari/8536.25)

Less waste (saves money)
Fewer broken glasses (saves money)
Less alcohol served overall (saves money)
Easier to monitor and limit alcohol intake by pax (safety and saves money)

Smaller spills.
And you must have big thumbs!

Waste and sturdiness, for sure. Those small glasses can take a good beating and still work fine. And while it may be more work to refill, the smaller volume can more closely satiate one’s thirst and alcoholic needs without turning the premium cabin into a club.