FireLance
Legend
I think that WotC's "blind spot" is that Favored Enemy was originally flavored as the ranger hating the type of creature so much that he got combat bonuses against it. From that perspective, of course, it makes no narrative sense for the ranger to "switch hatreds" regularly and without justification.I'm actually more dissatisfied with the first answer. Sometimes I don't feel these answers are well thought out (though are earnest as they can be). But there's a great wealth of game mechanics that cannot be retrained. It's that simple. Some things just can't be retrained. The Ranger could have their "favored enemy" type at first level and that's it. Maybe a feat at Paragon/Epic that's like "I got better at fighting this enemy too!".
However, flavor it as the ranger recalling combat techniques for use against specific types of creatures, and it becomes less limiting. Something along the following lines, for example:
Favored Enemy
Ranger Attack 1
You refresh your memory of the special combat techniques you have learned to battle specific foes.
Daily * Martial
Minor Action
Personal
Effect: Pick one type of creature, such as Humaniod, Beast, or Aberration. Until your next extended rest, you gain a +2 power bonus to weapon damage rolls against creatures of that type.
Ranger Attack 1
You refresh your memory of the special combat techniques you have learned to battle specific foes.
Daily * Martial
Minor Action
Personal
Effect: Pick one type of creature, such as Humaniod, Beast, or Aberration. Until your next extended rest, you gain a +2 power bonus to weapon damage rolls against creatures of that type.