There's definitely a CEO whose bonus depends on hitting a certain number of PSN accounts. I can only assume account info is being sold because why else would they care? It's either that or they eventually plan on charging PC players a monthly fee to play all their Sony games.
could also just be as simple as getting people’s feet in the door to their marketplace. if you already have an account maybe you’ll be fractionally more likely to buy other stuff in the store. multiply that by a few million or whatever… it’s not nothing.
Yea. Someone higher up at PlayStation (I forgot who, might have been the CEO) recently said that they believe PC gamers would buy PlayStations to play exclusive sequels to their PC games (like Horizon Forbidden west, which is not yet on PC). Forcing PSN accounts for their games on PC opens the door to getting a PlayStation just a little bit further.
Marketing. They want to increase PSN account numbers to increase their valuation, to have more data, and to make it easier for customers to move to their products/services since the account creation is already done.