I think this makes a lot better sense.

To buy and decide not to update is not a workable option because you are most likely going to be having issues when the framework is upgraded. Like trying to continue running a version 9.0 App on 10.0 base is not advisable. So to drop the barrier that keeps people away makes a lot of sense. 

If you make any App and 10 people buys for @50 is not as rewarding as when 500 buys @20.

Come to think of it, It is mandatory to maintain the App for the 10 clients and same update effort will take care of 500 clients. So it makes better sense to lower the maintenance costs.