I have similar impressions. I mostly fly from A to B intra-Europe, I want to rest on the flight, or work. I do not need 18 years old flight attendants or pre-packaged snacks, nor even a meal. This all disturbs on a short flight.

I need a clean aircraft and low hassle arrival/departure experience. CPH with fast track does better for me than most European hubs, even if I have to go to A25 (better than FRA, MUC, CDG, AMS or LHR). I also need relatively well behaving other PAXs, because they disturb my flight much more than SK could. SK pax are usually fine (also DY PAX are normally not too bad either). I also like a reasonable price, and this is what I usually get from SK on my routes.

Now I rarely fly PLUS, but usually the price for PLUS on my routes is only 30-50% more than the price for GO, and I think this is reasonable to pay for someone who does not have status, but wants the smooth travel experience.

I agree that SK long haul service in C is outdated, but I am cheap and fly Y. The service in Y is equally bad on most European airlines, unless you really value the IFE system (which I don't as I always use my own electronics, IFE is just there to provide some diversion during the meal). So I am a perfect example of a passenger that fits the SK business concept. I am unlikely to be taken over by competition (low cost are too messy and too inefficient, and LH hates people that fly so little as I do, and it offers mostly long connections through inconvenient hubs. Arguably for intra EU I have reasonably good experience with AB, which seems to have a somewhat similar business concept - simple flying).