Since the development of Windows Vista and the adoption of the Security Development Lifecycle, Microsoft has been touting a "responsible disclosure" attitude which means "don't say anything unless you're sure you can ship". While this in most cases is about reporting software vulnerabilities discovered by third parties to Microsoft (so MS can take their time to patch and test them), it also applies to any new feature announcements for a future version of a product. What they lack is a analogous "responsible removal" approach. Features are removed without any explanation being given, nor are all of them documented on MSDN. There's no one accountable when the infuriated user asks about a particular removed feature; nor does Microsoft provide a quick hotfix to resolve the issue or suggest appropriate third party replacements in all cases.
Features get removed during the beta too if the whole experience is not robust enough to ship (which is absolutely normal) but even then they are not documented. Case in point: Windows SteadyState. Its main component, Windows Disk Protection was improved upon to require only a logoff instead of a reboot to undo all changes, renamed as Guest mode and was included in the Windows 7 beta, yet it silently disappeared in the RC. Poor users who used it daily on Windows XP and Windows Vista are left longing forever. They are asking for it in Microsoft's forums: here, here, here, here, here, here, here, here and here. Other features which shared the same fate include: Native Bluetooth audio support, Accelerators for Windows (the Accelerator platform made it in), RSS Desktop Slideshow (which also managed to get in and is documented and supported in the INI theme file supplied but without an end user GUI), Removing beta features is perfectly normal though, in contrast to removing features shipping in an earlier Windows OS which is absolutely pathetic. In both cases, Microsoft does a poor job of documenting them and their reasons and an even poorer job of fixing them once users start complaining.