As a huge fan of the Warlord class, I'm not averse to this idea, but I think it would be difficult to iron out.
If you want to add inspirational-type features to the Fighter as class features, then you make it so that any Fighter you build has to have a high charisma, intelligence, or wisdom or else he's not going to be effective with his basic features. Whereas if you put those features in a separate class, then you don't have that problem.
Alternatively, if you have "battlefield command" as a theme/feats for someone who wants a high-cha/int/wis character, then you're making it something that anyone can take and thus going against the whole premise of making this something an inherent part of the Fighter. You also run into the problem that you have anytime you try to split a class's inherent definition off into a theme/feats: instead of those abilities being the baseline, defining abilities of that class, you have to get them slowly over the course of 20 levels to the exclusion of everything else.
Here are a couple ideas I just came up with:
1) Give the Fighter a "scheme" like the Rogue gets, with the difference being that the schemes grant different martial practices, so you could have, for example, a "Resourceful Tactician" scheme (gives abilities that are based on Int), a "Battlefield Bravo" scheme (abilities based on Cha), or "Force of Destruction" scheme (extra abilities based off Str/Con).
2) Give fighters an extra theme (double the number of feats). However, this could be really overpowered.