I think the licensing excuse can boil down to get better lawyers or draw up better contracts. I would have no licensing problems accessing my old games I played on a iPhone 4 on a iphone 6 just like I wouldn't have a problem playing games I played on an older android device on a new one. These 2 ecosystems the games are released to the ecosystem. When Sony was offering these cross buy games on PSP, PS3 etc why would they set it up to only run on PS3? They had to know they would be making new systems that would be more powerful. The Playstation Network was in existence. Why in the world would they ever agree on licensing that was so platform specific when every other walled garden was going the other way?
It's apples and oranges, really.
You're looking at it from the perspective of the the person licensing the content: of course Sony would prefer to license all content, on all Sony devices, for all time. That's a given, and when they go to write contracts that's what they [essentially] want.
However, those licensing content generally want the exact opposite. They want to draw the smallest license box possible -- specific platform, specific time frame, specific everything... because that opens up the possibility to renegotiate later, or to relicense in other ways. This is the same in every industry; as the content creator, you might only want to give one publisher of your book the right to do hardcovers in North America, reserving international and/or digital rights.
Now, the other thing you're forgetting is that a content creator in gaming is also potentially beholden to their own licenses. For example, Rockstar licenses a lot of popular music. They need to keep these licenses in mind when they then license content to Sony -- if you can only use a song for 10 years, you can't then go write a contract with another party to use your content container [game] for 15 years.... you don't have the legal right to. You're forced to limit your contracts, and Sony is also forced.
Likewise, Rockstar may want to have control over their own IP... and giving 'forever' licenses to Sony would prevent that. It's better, from Rockstar's perspective, to renegotiate on a regular basis. Your IP is effectively power... bargaining chips for the future. If you do this, we'll remove all GTA games from your store -- if you do that, you can have exclusive rights to our older GTA properties for 5 years, etc, etc [while these examples are made up, I'm just showing why it's in a IP holders best interest to retain as many rights as possible].
My point, basically, is that licensing is a complex, ugly mess... and assuming Sony can just require 'forever' licenses [on all future platforms, for all time] is just not the case. It wouldn't even be on the table as an option in many cases, let alone something Sony could require.
The transition to new hardware for consoles is nothing like an iterative device like iphones or PC. It's more like the shift from Apple IIgs to MacIntosh, or MacIntosh to Iphone, or whatever.