I think part of it is about retention … retaining all those users, especially those with high karma levels (or at least users who believe they have high karma) from abandoning the site and ending their accounts.>
If they were actually serious about retention of high karma users they could at least consider not suspending/ banning such users without a very good reason. My previous account on there was nuked for reasons I dont understand to this day, I would have happily stayed on otherwise. I have a temporary account there now which I had no intention of putting any money into - well now the one reason i might have been tempted to do so is going away anyway.
The award/ coin system was great, and I spent a bit of money on it, it was also a very good way to pay for or be paid for small international transactions - I assisted a few people with minor things and they paid my costs such as they were with reddit coin, saving them and me international bank transaction fees. I also liked rewarding intelligent and incisive comments that needed recognition as such.