why rare
Shy - "rare" because it is rare that the weather is bad enough that you CANNOT fly VMC and if it's a little bit worse then you CANNOT fly IFR either...
But it is nice to have the option, normally better to have more options than less
'Do' and 'need to' are different ...
and
Granted the A109 and a few others don't fly well without SAS (ref the Lynx ETPS IMC evaluations) - but some aircraft have excellent handling qualities eg the H500 is a breeze to fly very accurately IMC