ComfortablyNumb
Unquestionable Presence
Adding more notes is exactly what makes music more complex? And no, it doesn't make the music good necessarily but that wasn't the aim of that arguement, it was to suggest that Radiohead's music 'does' have substance.
As for what makes a band good I think that revolves around people liking it. I mean you may not like a band or a song but if a lot of people who know a lot of music really like it then there is a good chance it's good music.
Eg. Genesis; despite Sal's best efforts I cannot stand their music but I know that they have a huge fan base who know a lot of music and they don't just like Genesis but consider them the best band ever. You really have to respect that.
Same goes for Radiohead. There are a lot of people, like me, who hold them in the highest regard, that must count for a lot.
Taste is subjective no matter what. Just because there are many people that share the same taste in music as you and like a band that you do not like does not make that band a good band. If the amount of people liking a band or artist makes them good then take a look at what is currently popular. Does that make it good? You may call what is popular today shit, but to the people who listen to it it is the best thing around, but that still does not make them good.
IMO Radiohead is far from complex. Also adding more notes is just a part of making complex music. Radiohead is IMO an overrated band held in high regard for some unkown reason. They have a few good songs, but nothing special.