One thing everybody has forgotten is cost?
FS carbon bike (which was quoted in the OP) is about £2k+
Many have not got that dosh or want to spend that sort of dosh therefore hardtails make the sport accessible to many. You can have just as much fun on a HT at a fraction of the cost.
Pick the right frame material and even fully rigid works (steel takes out some of the 'buzz')
To get a FS to a decently low weight you are talking carbon or light alu frames at more than a grand a throw. You can build a SS or HT for about £300 – £500 easy and it will not be that much worse than your £2k+ bikes.
I bought the bike below 2nd hand for example for £350!
For me (only my opinion) Full sus = armchair!
The 'lets make it as easy as possible' runs out when you think well if that is the case lets get a trials motorbike or a jeep etc (make it even easier)? Or alternatively lets go on the road; no bumps!