I have a rule of giving 1 star rating to any kid's game that has them regardless of how well it's done and if my kids actually enjoy the non-gimmicky part. Milking parents by making their kids beg and nag them is an unethical way to earn money.
I believe that the primary way the market for children's toys and goods works, if you watch The Corporation they interview a psychologist that explicitly helps exploit this behaviour. So, you might find it unethical, but its the norm and avoiding it is like shopping for clothes that used no-sweatshop labour.
If he finds it unethical, it doesn't matter if it's the norm. He shouldn't do it. In both cases, there are clear and relatively easy alternatives.