In this day and age businesses can't be too picky with their clientele. Families are going to spend money and you'd be foolish to turn them away. They're probably going to spend more than the old gimmer with his pint of best as well.
Businesses forget that when they says "no kids" they pretty much are giving a very negative message that comes back to bite them.
When a business does that I deliberately avoid going there anytime, especially when we are meeting up with friends for an everning out.
Parents who happy to bring their kids to a pub for a meal tend to have a little bit more money to spend, after all why bother doing it when McDs (other burger/chicken/pizza establishment) is pretty much within 20 minutes.