Just to correct a couple of points firstly the bit about single engine aeroplanes flying at 25,000 feet kinda excludes all the PA 28's and other small fixed wing aircraft that regularly fly IFR in IMC at much much lower levels all without issue,not to mention the cloud base will be the same no matter how high you started from, and I would much rather pop out low level in a slow helicopter than a fast plane.
Secondly speaking from experience a stabilized helicopter is a lot easier to fly in IMC than an un-stabilized aeroplane , and even without SAS it's not a huge problem for short periods of time so long as you keep it simple and ask for help as you would only be IMC without SAS if you had a problem
I think the bigger issue is a lack of experience among the helicopter community of flying in IMC on shore, which has produced and maybe rightly so a very adverse opinion to it, where as in the fixed wing world it's just normal. The other thing to consider is that if it was easier to certify singles for IMC the equipment in them would rapidly improve as would skill and experience levels, lets not forget no one is going to force anyone to fly anything in IMC if they don't wont to! its about providing a means that minimizes risk for those who do want to
CBS