Remus I agree with you on quality and price. I'm happy to spend more for quality - and I noticed that a lot of the clothing I liked in John Lewis was more expensive than M and S.
But they have to get younger people in because they are a kind of 'loyalty' shop - they get people, and keep them. Their reputation is kind of based on the idea of being the store that clothes the family in basics. If they don't get younger people in - and I think they have to do that with some lower-priced, trend-aware clothes, they are going to lose an entire generation.
I also think there is a real place for cheaper versions of trend-aware clothes.
For example, there is a bit of a 70s vibe going on at the moment. I would really like a chiffon-look-alike dress, with gathered tiers, in a print, suitable for work. I kind of expected M and S to have something referencing that, at a reasonable price. But no.