We have many children, and have taken them in everything from Concorde to charter flights. No matter what class of travel they have all been taught from a very early age of the privilidge they enjoy and the behaviour that is demanded from them. I have always been proud of their behaviour on aeroplanes ( not something that is always the case in other circumstances), and that has been endorsed by some very complimentary comments from pursers and other crewmembers.
I can understand that other people do not expect to have to suffer discomfort from other peoples children and the price of premium class tickets acts as something of a natural defence in this regard. That is no guarantee of course, nor should it be assumed that unruly children are any more welcome in economy. As others have said it is public transport and you have to put up with the consequences of that reality from time to time.
Infants do cry, but usually for a reason. Parents do not enjoy the fact any more than other people and will nearly always seek to rectify the matter. Babies have a limited ability to communicate and nature has given them a very good method of establishing an imperitive and difficult to ignore signal. It is difficult to cry when they feeding, drinking and sleeping and they do do a lot of this.
The only way of guaranteeing who will surround you on a flight is to charter a private jet.