I understand what you are getting at, but the root of the matter is that there are different interfaces. I would have to say that the learning curve for Blender 2.5x is a lot less steep that it is for 2.4x. A lot of what we do depends on how we interact with the environment. There are books out there for 2.4x yes, but there are quite a few on-line resources for 2.5 and they are growing, since there has been a hushed agreement that things should shift towards 2.5x.
Example 1: While Yafaray, the external renderer that is made to work specifically with Blender, is working for 2.4x, their development has shifted towards integration with 2.5x since this is the future of Blender.
Example 2: LuxRender as well has taken on the philosophy that development and integration for 2.5x is paramount, since, again, it is the future of Blender.
Example 3: Kernon Dillon, who makes quite a few tutorials is putting together a 2.5x DVD.
Example 4: Blender Guru Andrew Price, again publishing stuff for 2.5x
Example 5: Blendercookie.com has Wes Burke and Jonathan Williamson producing works that have used exclusively the 2.5x series of Blender.
The basics are working just fine in Blender 2.5x, and lacking areas are getting better all of the time, but the basics are all you’re going to need when just learning. I know, I’ve been doing this for nearly 15 years in many apps. Ultimately it is the user’s choice on which direction to take, but for me 2.4x was a pain to get to learn and I took off with 2.5x which is a very capable app.
“If you don’t know Blender or CG then how would you know if it is a bug?” The screen turns white and the app crashes, and then the error reporting box comes up. Not much guesswork there.
““All the books and videos are based on Blender 2.49.”” Not true, see above. Many people who have published about 2.4x will or have switched to publishing about 2.5x. I think you will see that there will be a shift from the old to the new over time. Not saying this for the user, but for the development community as a whole.