1. Publishers have always wanted to limited how their games are used. Digital is about control. The only reason why publishers haven't pushed hard with digital is because as much as they love to call the like of GameStop the devil of this industry, they know ****ing off retailers isn't in their best interest. Publishers talk smack about GameStop but then give them exclusive editions and day-one exclusive DLC. Not really something you would think publishers would be doing with a group they argue is a scourge in the industry. It's also the same reason digital and physical pricing is essentially the ****ing same. Hell, here in Australia sometimes digital copies on the PSN and XBL are more expensive than retail versions.
2. How are they benefiting? They aren't making any money in the system you described. Arguably, they'd make less because trade-ins people make to buy new titles wouldn't exist any more. Plus, if I can share a new title with you I just bought there is nothing to compel you to go out and buy those brand new titles. And those release days is where publishers want to see gamers going out and picking up those new copies.
3. Microsoft have 2 rules: the 30 day deal and the game can only be gifted once. We know nothing about what restrictions publishers can put on their titles. I can assure you they will not be kind.
1. And so have developers. Even Steam/Valve do it already yet you don't see people complaining about the "control" because, "Oh well they sell me cheap games so I don't care if they can delete my library whenever they please." If you think developers aren't pushing hard with already you're blind. EA made their own client because of it, and Steam sales are continuing to grow, and it's cheaper for the developer to distribute digitally. They are pushing digital as hard as possible, and yet here you are blaming Microsoft for giving the developers (the secondary customer of their console) a feature they want. Microsoft needs to sell their console to the Dev's and Publishers as much as they do to the end user. Don't assume you're just being shafted because they can.
2. How are they benefiting? EXPOSURE. You get 5 people on your friends list to play game X, and perhaps they want to keep playing the game instead of waiting for it? Well now they have the incentive to purchase their own copy. Or perhaps you play a friend's game and you flat out love the game and when the sequel is released you decide you want your own copy. They've now netted a sale. Getting your foot in the door is the #1 priority of any sale. Sharing games does that by itself. Free advertising, free sales generation.
3. How can you be so certain? What evidence or even a suggestion that publishers and devs will lock the console down to the point of being unusable? How does that play to the consumer? Companies like EA, Ubisoft, Activision, etc have made these mistakes before with DRM, I doubt they'll do it again because the "can". In fact, i'm fairly sure they'll avoid it. If I recall, recently EA has even been toning down it's DRM level. The trends show a lightening of DRM from publishers, not an increase. Even Ubisoft, the god of DRM has stopped doing it. Don't assume the apocalypse when there is not but a single dark cloud in the sky.