Favored class change - why not?

[reflactions]

The rules provide that favored class can't be changed after character creation. I'm asked by my players to relax this rule and let them switch favored class. I'm in favor of allowing players flexibility in their character creation and development, so I am considering allowing switching to an extent.

Essentially, a character could switch favored class once the "new" class exceeds the old class.

So, for example, Griz is a fourth level halfling ranger (favored class ranger) who starts down the path of rogue. At level eight, Griz is a ranger 4/ rogue 4. At level nine, Griz continues as a rogue, and is allowed to switch favored class to rogue, essentially giving him five favored class bonuses.

Can anyone identify a good reason not to allow this as a house rule? (i.e. some way in which it could be abused).

[Rackdam]

Theres a feat for that.
You can do w/e houserules you want, it's not game breaking.

[Darksol the Painbringer]

While the Retraining Rules don't allow you to change Favored Class Bonuses, I'd consider looking over those rules and configuring a system conducive to those rules and offer it to your players.

As for it being abused, just make sure they can't do it whenever they want, make it require some downtime for them to switch it out (most Retraining rules require 5+ days, an identical time requirement here would be recommended to prevent abuse).

Also be sure to remind them that it's for the purpose of switching Favored Class Bonuses, not an attempt to gain more Favored Class Bonus stuff than what they should normally have.