My guess is based partly on a comment made by a Bioware developer, either here or in the (old) Bioware boards. He or she clearly stated that Ray and Greg's time were used to gather support, go to the meeting, secure money for the company's next projects. With the sale to EA, Ray and Greg did not have to do this anymore, but could concentrate on running their company.
And yes, they quit medicine, I think they were working as ER doctors?, to establish Bioware. Or rather Bioware was created first. They first 'game' they worked on was some sort of medical software programme that could help doctors do analyses and diagnoses (I think?). And then, in an interview (maybe on evil avatar?) they told that in 1995, they took a big leap (of fate) and started the company, Bioware, maxed out all their credits card and were really really scared about not making any money at all from BG1. However, it all worked out in the end. And yes, the good doctors are business people too. So they also looked for ways to expand their business - and they did so by selling (out?) to EA.
However, thinking that the DLC is EA's idea would be giving EA way too much credit. Ray and Greg from Bioware did say, many years ago, that they wanted to give players and gamers incentives to buy the game, not punish them. They would do this with DLC as a way to encourage players and gamers to buy games at their original release date.
I also agree that all this dlc and unlockable items business is way too much.