The problem is - Bards weren't solely musicians. They were storytellers, acrobats, spies, personal entertainers, jugglers, scribes, both narrators and orators, scholars, even scientists among other things. Besides, I myself am musician, and I consider myself lawful - I have a strict code of conduct that I adhere to.
Crippling one class because of other one's flawed progression doesn't sound like intended thing. Besides, 2 monk levels provide loads of bennies too, and monks are as lawful as paladins, and can mix well (if not as well as bards or sorcs).
Requiring a class be neutral or chaotic and not lawful is hardly something I would describe as "crippling".
Really? Crippling? You'd use that word? It's not like the class ceases to function and no players thus far have imploded as a result of being non-lawful.
What's really bizarre in your incredibly ridiculous usage of "Crippling" is that you entirely gloss over paladins being "Lawful Good", and Monks being just as Lawful. Are they similarly "Crippled", do they require a great deal of bedrest for their convalescence?
I mean I guess you could hide in semantics on this one...
1. A person or animal that is partially disabled or unable to use a limb or limbs: cannot race a horse that is a cripple.
2. A damaged or defective object or device.
tr.v. crip·pled, crip·pling, crip·ples
1. To cause to lose the use of a limb or limbs.
2. To disable, damage, or impair the functioning of: a strike that crippled the factory.
I mean.. I SUPPOSE you could say being required to be nonlawful is crippling (and therefore the function of the class is impaired) in the same way I could describe myself as crippled from receiving a papercut and therefore my ability to type is impaired...
But really man... CRIPPLED?