Most of the inconvenience around DRM is because implementations can be buggy and it's often built into sub-par software but I don't think it's necessarily by design. Services like Steam and Netflix are doing well by providing more convenient implementations.
The endgame for DRM could well be that it becomes totally transparent, you consume whatever media you want on whatever device you want whenever you want and you get a bill every month based on some complicated price matrix and people will just pay it the same way they do their phone bill.
DRM is necessarily inconvenient by design. It exists to prevent customers from doing what they want to with the product. Perfectly reasonable actions become impossible or illegal due to DRM. I'm not sure how that's convenient in any way.
The idea would be to allow the end user to do anything they wanted with the product but to price discriminate between different users and different use cases. So it wouldn't be less convenient , simple more expensive in some cases but perhaps cheaper in others.
This end user always wants to be free to make copies of his products, use them without an internet connection, share them with family members, and use them on any platform of my choosing, even converting them to a different format if necessary.
No DRM system will allow me to do that, because that fundamentally challenges their control over the product. I'm happy to pay more for a product without DRM, but they're usually not available.
From a legal perspective you were never free to make additional copies for others without the permission of the copyright holder. Even format shifting was controversial in some jurisdictions.
The idea of DRM would be to allow you to do these things, but have a mechanism to bill you for them. The problem at the moment is that the ecosystem for this is incomplete.
It is absolutely legal to make a backup copy of a copyrighted work. [0] It is also legal to lend your purchased work to anyone you choose (making a copy). DRM prevents you from exercising your rights under the law.
The endgame for DRM could well be that it becomes totally transparent, you consume whatever media you want on whatever device you want whenever you want and you get a bill every month based on some complicated price matrix and people will just pay it the same way they do their phone bill.