Even if it's only 1% that's still $6 million bucks. I suspect there are lots of people like me who have the technical ability to flash a custom ROM but just don't want to spend the time and effort on it. Reading through a 200+ page forum thread and dealing with the rough edges of these custom ROMS requires an investment of time. There are also all the business/enterprise IT departments who aren't going to touch a random custom ROM they found on the Internet. They need some official upgrade path. Most companies don't want to buy a new fleet of phones very 2 years.