Simpsons have put out a few limited editions before.
It is a good sales tool to have something "special" or in limited quantities as this brings in users who normally would not be in the market for a new brush because they think they might "miss the boat" on the limited run of product.
There is something fascinating and irresistible about something "new" Just look at all the "new" cheese burgers that come and go.
I know horses for courses and everyone has different taste but a shaving brush , to me , is something that should be classy, regal and reserved not funky and radical. Especially not from Simsons who are considered the pioneers of shavin brush classicism.
My thoughts exactly hedonist but as with all these things, YMMV.
There not Limited Edition's as such, more limited production brushes. I'm sure that once those are sold and you asked them to make you a brush, they would.