...and why so few features are being included in the minor updates (GDR*), and most are related to hardware?
WP 7 => November-2010
WP 7.5 => September-2011, 11 months after WP 7
WP 8 => November-2012, 13 months after WP 7.5
WP 8.1 => February-2014?, 14 months after WP 8
WP8 took so long because they were switching to the Windows kernel and that's a lot of work, WP 7.5 was still using the old Windows Mobile kernel. But once that work is done, they should be working in features, why aren't those features coming to the users?, where are the fixes to the annoying bugs?, If they are developing the universal search or a notification center, why do they wait 14 months to release everything?
I think the reason is that 8.1 is not just a pack of new features and bug fixes, 8.1 is a major revision of the OS. And the new features can't be backported to WP 8 because are integrated into a modified OS structure.
WP8 hasn’t changed much since WP7, so probably now that they have a solid foundation is a good time to introduce the design work done since 2010 and the new elements of Windows 8, to release an much improved Windows Phone.
In the internals, they are ditching the last pieces of the old platform and adopting the Windows 8 parts.
This is the evolution of the internals since WP7 (I'm not a dev so It could be wrong):
Windows Phone 7
-Silverlight XAML
-XNA Games
-Silverlight CLR
-Windows CE Kernel (sames as Windows Mobile)
Windows Phone 7.5
The same internals as WP 7.
Windows Phone 8.0
-Silverlight XAML + Some WinRT 8 APIs
-Partial DirectX (same as Windows 8)
-CoreCLR (same as Windows 8)
-Windows NT (same as Windows 8)
Windows Phone 8.1
-WinJS (same as Windows 8) ?
-WinRT XAML + WinRT APIs (same as Windows 8) ?
-Complete DirectX (same as Windows 8) ?
-CoreCLR (same as Windows 8)
-Windows NT (same as Windows 8)
With these changes the convergence with the Modern UI part of Windows 8 would be almost complete. The same kernel, runtime, API for games, API for apps and UI components. Some apps could even run in both platforms untouched, but the majority would share most of the code with different front end for each form factor.
If the new features of WP 8.1 are built using these new components is another reason why they can't be backported to WP 8.
So I hope Microsoft will surprise everybody with a really good release next year, but all this is just speculation.
WP 7 => November-2010
WP 7.5 => September-2011, 11 months after WP 7
WP 8 => November-2012, 13 months after WP 7.5
WP 8.1 => February-2014?, 14 months after WP 8
WP8 took so long because they were switching to the Windows kernel and that's a lot of work, WP 7.5 was still using the old Windows Mobile kernel. But once that work is done, they should be working in features, why aren't those features coming to the users?, where are the fixes to the annoying bugs?, If they are developing the universal search or a notification center, why do they wait 14 months to release everything?
I think the reason is that 8.1 is not just a pack of new features and bug fixes, 8.1 is a major revision of the OS. And the new features can't be backported to WP 8 because are integrated into a modified OS structure.
WP8 hasn’t changed much since WP7, so probably now that they have a solid foundation is a good time to introduce the design work done since 2010 and the new elements of Windows 8, to release an much improved Windows Phone.
In the internals, they are ditching the last pieces of the old platform and adopting the Windows 8 parts.
This is the evolution of the internals since WP7 (I'm not a dev so It could be wrong):
Windows Phone 7
-Silverlight XAML
-XNA Games
-Silverlight CLR
-Windows CE Kernel (sames as Windows Mobile)
Windows Phone 7.5
The same internals as WP 7.
Windows Phone 8.0
-Silverlight XAML + Some WinRT 8 APIs
-Partial DirectX (same as Windows 8)
-CoreCLR (same as Windows 8)
-Windows NT (same as Windows 8)
Windows Phone 8.1
-WinJS (same as Windows 8) ?
-WinRT XAML + WinRT APIs (same as Windows 8) ?
-Complete DirectX (same as Windows 8) ?
-CoreCLR (same as Windows 8)
-Windows NT (same as Windows 8)
With these changes the convergence with the Modern UI part of Windows 8 would be almost complete. The same kernel, runtime, API for games, API for apps and UI components. Some apps could even run in both platforms untouched, but the majority would share most of the code with different front end for each form factor.
If the new features of WP 8.1 are built using these new components is another reason why they can't be backported to WP 8.
So I hope Microsoft will surprise everybody with a really good release next year, but all this is just speculation.