Car appreciation... the aesthetics, the engineering, etc

Nothing, but then who wants to settle with "pretty good"? If you're going to go B road storming or do trackdays, you're going to eventually reach the limits of handling. The suspension design is also 50 years old, bringing it into the 21st century is no bad thing.

The guys who went racing didn't run standard suspension, neither do any of the race series now. Out of the factory the tolerances were good old Rover/BMC quality (read: massive), and think how they've been affected over the years, adjustable suspension allows you to bring the settings back to what was originally intended, or go beyond that and go more aggressive.

But this is a road car, not a racing car. Stuff for track cars isn't necessarily good for the road.
Road cars drive at lower speeds on worse road surfaces with dodgy camber and carrying more weight.
It might be a 1959 design, but a standard Mini (with not-knackered suspension) will run rings round pretty much everything else on a twisty B road as it is. There really isn't that much room for improvement on the handling front, so you spend a lot of money for a setup that isn't really that much better. Most reported improvements probably just come from replacing knackered components with new ones.
The area where Minis need suspension help is their bloody awful bouncy ride, not handling. If it was me I'd be looking at the Moulton Smootha-Ride kit http://www.minisport.com/mini-spare-parts/info_MSLMS0400.html. And you can do the camber as well.