Looking at it another way, most companies would sell one of their vice presidents to figure out a way to get 50% more business. This could be an easy route to increasing revenue.
It's probably less than the 50% bump in revenue, and likely cheaper than building it the first time since you can reuse tons of assets...(of course provided that it's 50% of something sufficient).
Let's be realistic about what we're talking about here, most phone apps are not multi-million dollar, multi-year AAA development efforts. They're typically made by a couple guys over a few months. That's why the typical app per-unit price is so low compared to the typical app-per unit price for desktop software. In the case of a "AAA" title, we're likely talking about something that's multi-platform anyway...code is generally cheap, art assets and design is expensive. A great example, Plants vs. Zombies for desktops is $20, for the iPhone it's what...$4? Yet it was completely worth it for PopCap to rebuild the entire game for the i-platforms (twice!)
In other words, if it's not worth doing it for a 50% revenue bump, it probably wasn't worth doing it the first time either.
