It's easy to say "XYZ is dead, time to replace it with something better". Another example is the Win32 APIs are hideous (look up everything SetWindowPos does) and need replacing.
In the real world though, backwards compatibility reigns supreme. Even if you do go and make a better thing, nobody will use it until it can do the vast majority of what the old thing did. Even then, switching is costly, so a huge chunk of people just won't. Now you have two systems to maintain and arguably an even bigger mess. See Win32 vs. WinRT vs. Windows App SDK or however many else there are now.
So if you're serious about improving big mature platforms, you need a very good plan for how you will handle the transition. Perhaps a new API with a compatibility layer on top is a good approach, but the compatibility layer has to have exactly 100% fidelity, and you can never get rid of it. At the scale of these platforms, that is extremely hard. Even at the end of the day, with a huge compatibility layer like that, have you really made a better and less bloated system? This is why we tend to just muddle along - as much as we all like to dream, it's probably actually the best approach.
>Perhaps a new API with a compatibility layer on top is a good approach
The opposite would make more sense. Have a transpiler or something to the 'old' API (very natural, given it can grow with the new API and you don't have to implement the entire 'old' API), while new apps can slowly transition the 'new' API.
In the real world though, backwards compatibility reigns supreme. Even if you do go and make a better thing, nobody will use it until it can do the vast majority of what the old thing did. Even then, switching is costly, so a huge chunk of people just won't. Now you have two systems to maintain and arguably an even bigger mess. See Win32 vs. WinRT vs. Windows App SDK or however many else there are now.
So if you're serious about improving big mature platforms, you need a very good plan for how you will handle the transition. Perhaps a new API with a compatibility layer on top is a good approach, but the compatibility layer has to have exactly 100% fidelity, and you can never get rid of it. At the scale of these platforms, that is extremely hard. Even at the end of the day, with a huge compatibility layer like that, have you really made a better and less bloated system? This is why we tend to just muddle along - as much as we all like to dream, it's probably actually the best approach.