Actually CA hasn't banned Nitrocellulose lacquer 100%, but there are STRICT regulations. The big problem with it is that they want the VOC levels down so to do that you have to have such a low solids content in the lacquer that it just isn't cost effective to do that.
From what I understand, Fender's moving Guild to tacoma has nothing to do with the lacquer issue (since Fender has an AMAZING filtration system that allows them to spray nitro) it's all about space. That's the reason that the electrics were discontinued was that they just didn't have enough space in corona to make all the fender stuff AND the guild stuff too. The Guild rep called the store where I work and told our VP that they are planning on reintroducing the bluesbirds soon and we've already placed an advanced order for them. I'm keeping my fingers crossed.
In regards to the poly versus Nitro finishes, yes there is some mechanical adhesion going on there ( the finish has to bond to something after all) however there are many reasons why the tone of a guitar changes over time (depending on what type of guitar we're talkin' bout here.)
NitroCellulose lacquer on it's own is quite brittle, and has a poor build characteristic. It's the plasticizers (sp?) that make it more flexible etc. Over time the plasticizers evaporate out of the finish leaving it brittle and some shrinking occurs. It's still bonded to the wood but since it's a bit thinner and more brittle it's easier to chip off.
Personally I would never get a guitar with just an oil finish or no finish at all because you have ZERO protection on the wood. That's probably the biggest reason to finish your guitar (to protect the wood) all that moisture absorption and loss and your guitar would warp and twist etc.
I really hope I'm not coming off like a jerk or anything, as my intent is not to sound like a know-it-all. Just thought I'd post my opinion on the matter.
Cheers!
Bob Nelson