They're not, they're a great way to keep families and young children who can't ski very well out of the park, and they're a great stepping stone for kids and everyone else that wants to get into riding park, but not yet have the skills.
The problem arises when the resort fails to comprehend that a funslope and a snowpark are linked together, as one is the natural continuation of the other. To only focus on a funslope is bad business, as the people that start out on the funslope will want a snowpark once they get better. And when you don't have one, or the one you have is shit, those people will go somewhere else, and you have just lost yourself business with arguably the key demographic of a ski resort. Stupid move.