Why does Cary Audio keep discontinuing good amps?

Two more reasons:
The Cary 120 amp needed a re-design because it runs too hot inside the chassis. The british press caught it, the american press went GA-GA over it.
The SLP-05 preamp has a Tube Engineering 101 mistake: the tube rectifier is mounted horizontally inside a slim chassis with very little ventilation. Rectifier failures are very common and expensive.
I believe that after Dennis left, they are clueless technically and from a marketing POV.

I have heard of two SLP-05 failures in my neck of the woods in the past 12 months.
These tubes are supposed to last for ages, 10 years for new production, 25 years or more if one is lucky to find an NOS Mullard rectifier.

Look how cramped and poorly-ventilated is the rectifier and decide for yourself if this is good or bad design:
http://www.asi-tek.com/sitebuilder/images/IMG_2986-471x349.jpg