That has the problem, though, of forcing the multiclassed character to pay feat taxes in order to approach the heart of what the character concept is about. This is on top of the problem that 3E-style multiclassing is generally very poor for characters of two different archetypes. The reason many fighter/mage PrCs and things like the Mystic Theurge existed is because that kind of multiclassing just doesn't work without patches and bandages. If you add feat taxes on top of those kinds of problem, it just makes the entire concept worse.
So, you're making a case for better multiclassing? Sounds good to me. But again, if multiclassing works at all, then a fighter/wizard multiclass should be able to perform the "magical warrior" role just fine. If not, it shouldn't exist.