There is a huge disparity when it comes to the cost of apps these days vs the salaries required to sustain the engineers who make those apps. Even at $10/pop, you need to sell a lot of apps just to sustain the salaries of very good engineers, and THIS is what makes great products vulnerable to acqui-hires.
The problem is that the $0.99 model of the App Store makes a $10 app look ridiculously expensive, especially when there are free alternatives out there, even though it's only 2 Starbucks coffees. And even though $10 is worth it.
It's the price of the apps that have drastically lowered the expectations of what people need to pay for software, and this goes in direct conflict to the rising costs of great engineers' salaries.
I'm not sure what the exact price point is, but my guess is that people need to start getting used to the idea of spending $30-50 PER YEAR in a subscription model for a great app in order to create enough monetary incentive for the developers to keep their products alive. Otherwise Google and Facebook will continue to drop the bills and pick off the best teams who eventually get tired of the smaller comparative payoffs that these apps bring in.