I don't think teamwork or group effort is the issue here.
Spellcasters (wizards, clerics, druids, etc.) casting spells to enhance their team mates is a step up from spellcasters only using their magic to enhance themselves.
However, some would consider giving non-spellcasters some ability to enhance themselves to be a step up from that. At least from 3e, there have been a few examples of such abilities, like barbarian rage and monk powers.
I suppose if it really bothered people a whole lot, they could add a ritual to the game, something conceptually like: For practically no real cost, the recipient of this ritual is now charged with magic such that any non-mundane effects available via exploits are operative for 24 hours.
There. For each power taken by a martial character (the actual ones taken in your game, no need to be exhaustive) decide which ones (are parts of ones) are too magical for your group to buy as a mundane effect. No ritual, can't use those powers. Since it is a ritual, you can also decide how this works:
1. It is a free ritual that every martial class knows. They buff themselves every morning as part of their exercises.
2. Anyone can do it, but they have to get access to ritual casting same as normal. Individual groups can depend on the wizard to do this for free, or they can burn some feats for backup/supplement.
3. Via knowledge skill required or other limits, only certain casters get this easily.
4. Wizards and Clerics and the like buff--so they get it and no one else can. Your fighter can do Come and Get It because the Bard magicked him up every morning.
5. Get really nit picky and say that the ritual only lasts for a power until discharged. After every encounter, you have to rebuff.
6. Go all 3E on it, and say that the ritual only lasts for a short time (but has a very short casting time, probably minor). Unless you ambush someone, the caster has to buff the martial class as the fight gets started.
Or you could just ignore all that handling and say that something like that happens as pure fluff, and leave the mechanics alone.
