AA doesn't owe you compensation. It also doesn't owe you any customer service gesture such as miles/voucher.
You booked a seat, you got a seat. Why was it a middle seat? Maybe that's all there was by the time you chose your seat or checked in. Why a baby next to you? Because people with infants are permitted to travel. Why did it drool on you? Ask the baby.
You got the 100% correct response from AA. Move on.