That is not the point. The restaurant has financial numbers to hit, that is calculated by an algorithm that estimates how many adult and how many children meals are purchased. The lower price point for the children's is offset by the higher price point for the adults. SO the numbers of how many of each price point do matter. And if the financial goal is not met - they will fix it whether that is to raise prices, enforce 9 and under, prix fixe or something else. There is an easy fix for guests - just don't eat at those restaurants where you can't get your monies worth.
And I doubt most would want the meals to be regular and small. The price point would have to change. A kids meal now at $13.00 would likely jump up to $22.00 or more, and the regular meal would go from $38.00 to $52.00. It's the only way to get the end dollar point they want. You would have lots of upset parents of younger kids, and I think that would be a big impact on ADRs.
I get it I do, I used to love CA Grill in the old days when food and service was exceptional. When that declined we'd fill our table with appetizers and sushi. We'd tell the server bring check with food so we can turn your table fast. I totally get why they went prix fixe and likely will stay until ADRs slow, we had a good run. Last trip we did Topolino for very late "dinner" and filled table with appetizers. Our best service ever. We went during a slow timeframe and never felt rushed. If I had to pay prix fixe there - yup, I'd likely only go every so many years.
The great thing is that every single dining decision we make is optional. If TS is not working for you price, portion etc then there is plenty of quick serve where you can get a kid's meal or easily split an adult. That will never change because (1) the cost of enforcing would be prohibitive (2) the price point difference really isn't worth the fight.
NOTE: Each restaurant is it's own profit center (so all the snacks eaten don't help them make their numbers) with their own budgets, own managers, own menu decisions and now we are starting to see own rules coming in to play. And remember right now there is no Dining Plan which forces adults to use adult credits at TS. Yes, some might share meals but I imagine when most use the
DDP, the thought process doesn't worry about the nickel and diming, DDP was a pretty steady income for restaurants.