As somebody who constantly rips out the overcomplicated soldier to replace it with either kork or the blue guy for every project even minutia testing of new versions... I'm all for something more generic and usable, I haven't read links, I'm too lazy but if you cannot distribute mixamo then it serves little purpose for this particular discussion. it is, however, another tool in the toolbox, and if a new default character and modified underlying structure are implemented then any tutorials with other tools need to blend in with that system.
One of the complexities of the system is the issues around first-person and third-person with first-person being more about weapons(or tools) than it is about character, this is not really discussed anywhere in any useful documentation, the discussion may well be had about how this two interoperate, which I guess is also useful but they still need to be documented distinctly.
Animations are key here since they are also hardcoded sections of this in the engine, not sure how other engines handle this, but I have often heard people complain about flexibility, whether these are based on actual lacks or perceived lacks I don't know, never really used any other engines, nor have I ever used any non-torque provided animations, even with non-torque models I have rigged a torque skeleton to the models, just because of the masses of animations available for me the mega animation pack, the mack/fack pack and of course the CMU released animations (yeah I know there's a lot of useless animations in there but maybe some people might use them).
I'm slightly concerned about the open-source zealotry, while there are open source tools and often the best choice and everyone is entitled to use those, they are NOT the only tools and not always the best choice, any contrary opinion is precisely that opinion... this is why annoyingly the current character model is supplied in a completely (a piss poor IMO) non-partisan format, there are other formats, which are far more commonly used and stable which could be used, and this should also be discussed, limiting to blender just because of the software is open source is a poor reason for choice.