> Besides the slightly interesting stuff Tamron is doing, why on earth would I want firmware updates for a lens?

Improved algorithms for focus hunting, diminishing chromatic aberration (most of it is in the glass but some positioning can tweak it).

I get it, there's not a lot that will happen there, but some of that stuff will be useful on an investment that can easily be several thousand (I don't get into the wildlife telephotos, but two of my lenses were $3,300 or so - RF 85/1.2 and RF 28-70/2).