jack of all trades is such a derogatory term for balanced playstyle.
I hate this stupid idea to make every army have some specialised playstyle like a league of legends character. They should be less specialised, more capable of different styles, it doesn't matter if there's overlap, it makes it less rock paper scissors. It's not a video game where you can effortlessly drop one army and play another, people should be able to play their models in multiple ways, and let's face it it's the models that attract people to armies not playstyles. It would also lead to less skewed lists, and more balanced ones which frankly make for more fun games.
How much they play the army depends on the playstyles.
And alot of us have multiple armies so if every army has nothing unique about them then what's the point in having 16 armies books? ...just reduce it to 5-6 books. All the elves could be merged. Some people might complain about the names of units but that is easily solved by putting multiple 'fluffy' names in the unit entry.
Very similar to kings of war.