I am a programmer myself and a very good one. It is impossible for me to beleive that removing such an easy to program feature has anything to do with the reliability of Explorer. It's not rocket science to create a database where for every folder in your system you keep track of various other items, such as the window size and position of the folder when it is opened. So I doubt it has anything to do with reliability, especially since a much less reliable part of Windows, the registry, has existed for years to hold important data.
No one is ever going to convince me that a real relational database is less reliable than the hierarchical Windows registry, which just about anyone and any program can corrupt without any problem. I am not saying that the registry is a wrong idea, as it certainly is not, but that keeping track of folders is a baby programming task which can be made as reliable as you want to make it.
Almost certainly Microsoft removed the individual folder view because some GUI 'genius' told them that it confuses mama-poppa computer user, and they bought this idiotic notion because that, in their opinion, is their ideal money-making market. Its simplification to the point of inanity, and everyone from Microsoft to the various IM/E-Mail/Social Networking providers and Best Buy software boutiques are now following it to the deteriment of anyone who actually wants to use software and understand how to do anything decent with it.