The Hollies: highlier regarded if they split up in 1963?

Of the successful bands of the sixties I always get the impression that the Hollies have been forgotten. They were not as big in the US, but in many European countries they scored a big number of top ten hits.

I am trying to figure out why the band is not relevant today. Maybe the reason is that they "spoiled" things by releasing shitty music. If they hadn't recorded any albums or singles, people might not have such a negative impression of their music.

So what should they have done differently in order to remain relevant or to be highlier regarded in retrospect?