Fuck trendiness and fuck salt. That's all commercial appeal to people like that. So many people only know Floyd for the Wall and Dark Side. Just like so many people only know Zeppelin for Stairway.
Dark Side was the first commercial success for Floyd. Before that, they we're pretty underground. The albums before was a lot of attempts, but didn't quite make it. Their first single released (Arnold Layne), had a lot of potential, at the same time though, Procol Harum released "Whiter Shade of Pale", and that over took them.
So many elements went into Dark Side to make it such a success. It was on the charts for 14 years for God Sakes.
It's a conceptual album, about stages of life, emotions and man's mentality. Everybody contributed, Alan Parsons did amazing work as a producer, I can go on and on.
Wish You Were Here is a follow up. Yes, Shine On is about Syd ("Come on you Piper"). Have a Cigar is about their sudden rise to commercial success. Wish You Were Here as a song is one of the first times Waters begins to write about his troubled, war torn childhood. Welcome to the Machine, I know there is something to it, I've never been about to pin it though. It's my favourite song to get lost to though.
Animals as a darker conceptual album. I don't want to go into that. I forgot what I'm typing about.