One single ringtone, Crazy Frog, made its creators a cool half billion back in 2006: http://communities-dominate.blogs.com/brands/2010/09/welcome... Sometimes you're just in the right place at the right time. Also, price/availability makes a huge difference--how many platforms was Angry Birds sold on and how much did it cost compared to Mario?
Lady Gaga may outsell the Beatles this year, but in 2015 it's almost near certain the Beatles/Elvis/Frank Sinatra and other classics will still be selling. There is always going to be a demand for new product, but the iconic games/bands/movies are still as relevant as before and there will be demand to have these classics ported to the new medium.
We're talking about an old game on a device it wasn't meant for, there's no way your average consumer would rather that over a game built for the touch interaction on a device.