From IOS 15.1M&T release notes at http://www.cisco.com/en/US/docs/ios/15_1/release/notes/151TFEAT.html
The memory recommendation tables have been removed from the Cisco IOS Release 15.1M&T release notes to improve the usability of the release notes documentation. The memory recommendations that were provided by these tables are available through Cisco Feature Navigator.
So the only way to check the memory requirements is to use that piece of Java crap called the Feature Navigator that takes hours to get a result – it might be accurate but its not much use when you are looking for a quick check in order to do some rough guesses on costs for project.
Lazy, cost saving, or what ? This is core documentation and should not be removed.
Second, it should not be assumed that access to the Internet is a given. I have the release notes as a PDF on my iPad since most of the time I’m offline.