You don't think they want to expand their subscriber base beyond the plastic box? Maybe not in June but in the longer term surely. PC gamers aren't going to subscribe just to stream everything. Not in any great number. Hence why PC Game Pass exists and not just the cloud.
It's hard, because they need the entire infrastructure to support the platform on PC. The streaming part is easy, they already have it done with PS Now and it's basically just a video player, but downloads require license checking, support, updating systems and basically an entire new launcher they're probably not going to do. It's unlikely they're going to bother with the couple games they release on PC, at the moment. Also, what would happen with the third party gamesyou get with the subscription? They're also added as downloadable in your service and keep the cost of having to maintain them? MS does that because the games are in the MS Store anyways, so they might as well just service them.
Also, people love to have new launchers, as we know.
(and before you tell me how EA Play is in Steam, Steam only charges the money, everything else goes through Origin)
EDIT: though, I will say, Sony is definitely making a push for its PC initiatives, as shown by their recent hiring posts, so who knows what the future might bring!
If you haven't played UC4 before, you are in for a treat. Lost Legacy is good also, but I think its well overrated on this forum.
I agree, UC4 is the gold of the franchise IMO, U2 being a really really close second.