Why would anyone want class AB amp when class A always sounds better ?

Yes, mapman, done right they do. 
Gryphon, Accuphase, Pass, Luxman etc.
"Some feel" funny things, that's for sure.

Who the fuzz are you to be here ? Go home.

D'Agostino amps might be an exception in that they are top level and can compete with almost any SS.

Class A amps require devices that can handle more current or more devices in parallel in order to produce the same power. Higher capacity devices or more devices in parallel (or both) add complexity and force the driver stage to work harder. This is not "free" from a performance (sound quality) perspective. So it's not at all clear that a class A amp will sound better than a class A amp, and certainly not for the same build cost.