> So why not license the shape then?
Because - until it makes its way through the courts - it’s not established that Fender has the rights to claim ownership of on the shape in the first place.
In the US, there’s three routes for that - design patent, trade dress and artistic copyright. AFAIK they don’t have a design patent. Trade dress is hard to prove association - would most people on the street say “yep, that’s 100% a Stratocaster” if they say the outline? Probably not. The shape isn’t separate from the functionality so artistic copyright hasn’t upheld either. The fact that Fender has not successfully enforced copyright concerns for over 70 years is also a sign that they never had IP protection on the shape.
In the US, I'm pretty sure they have no protection. They lost a US case to establish a trademark in 2009 [1] (2009 article title says copyright, but text is about a trademark suit). A design patent would have expired, unless it was filed in 1954 and was pending until recently or is still pending... US patents filed before 1995 don't start their validity period until issuance, but that'd be a big stretch.
It's possible there's a US copyright claim, but on a 1954 design, you would have to have registered it, marked the works with the copyright (on at least most of the copies), and timely renewed. There's also, IMHO, a solid question of if US copyright applies to the shape of a guitar. If they had a strong case, I think they would have tried to enforce on it in 2009 when they tried to enforce on trademark.
[1] https://www.musicradar.com/news/guitars/fender-loses-guitar-...
There’s a story, possibly apocryphal, that the first electric guitar demo was a bunch of strings nailed to some basic lumber and it received a negative reception. The designer went home, tore apart his acoustic guitar and mounted the electronics inside. The sound was not changed by this. The critical reception however was much improved. And the rest is history.
The shape might not be purely functional—and that seems to be the basis for their attempted lawsuit.