Question: Our little boy is 2 years old, and we are still giving him a large amount of formula milk at bed time.

He is not a good eater, and we don't want him to get hungry in the night.

Is it recommended to give extra milk (he often has at least 15 fl oz), or to let him go hungry so he is forced to eat his food?

Answer: 
I saw one of my sisters-in-law go through a similar situation with both of her girls (one is five; the other is four), and it looks like I'm gearing up to go through the same thing with my daughter (18 months).

Her girls (and mine) were/are big drinkers and drank/drink A LOT of milk. They ate (and still eat) very little. One can make the argument that because they drink a lot, they aren't super hungry at dinner time which is probably a somewhat valid argument. Unfortunately, when you have a child whose weight and height consistently fall in the 5th percentile and below, you get into the habit of doing whatever you can just to get calories into their bodies. My daughter and my SIL's youngest still wake up in the middle of the night and want milk. My SIL's oldest no longer does this.

As long as there is no evidence to suggest that your child is having trouble with his oral development (he can chew different textures, he talks, and does all those things that he should do at his age), then I'd say it's probably ok. Not ideal, but ok. He's probably not going to go to college with this same strange quirk. Maybe you could try weaning him--giving him less and less milk at bedtime until he gets none. If he's still getting whole milk, you could try switching him to 2% and the reduction in fat might encourage him to eat more solids.

Regardless of what you choose to do, it's been my experience that they more or less grow out of it eventually. My niece did, my daughter is starting to outgrow it, and I'm willing to bet your son will, too.
Once he drinks your pediatricians quote of whole milk and maybe a bit more he has to learn that meals are meals and really food is what big boys eat. Ensure that he does his best at dinner, reminding him that breakfast is far way. Then slowly wean him off of snack (if bed time is many hours after dinner obviously don't take snack away entirely) and convert that snack to include solid food. He is a person and needs to eat like one, not like a baby any longer. This is not making him grow up too fast, it is teaching him proper eating habits while you still have the power to interviner in his activities.