Glenn Frey the most important member of the Eagles because he founded the band. Without him starting it, The Eagles would never have existed. Additionally, he played guitar and piano, which are some of the primary musical instruments in a band. He was one of the primary singers with lead vocals on many well-known songs.
Based on what has been said about him over the last few days, it is clear that Glenn Frey was in fact the glue that kept the group together. He is said to have used sports psychology in terms of his dealing with group members. He knew how to assess the strengths and weaknesses of each band member in order to help create the necessary balance need to achieve success.
While Frey was an amazing artist and contributed a lot to the Eagles and his own solo career, all of the members of the Eagles were amazing musicians and singers, contributing so much to every song that they sang. The Eagles could put any one of their members in the front and they would all equally rock.
Glenn Frey was a huge part of the Eagles as a co-founder, a great writer, singer and musician. The Eagles were great because of the way their parts came together and the way the voices blended. He is a huge musical loss. He will be missed, but the Eagles worked so well with Don Henley and Glenn Frey together, writing together and with Joe Walsh playing guitar. Felder, Schmitt and Meisner were also key parts, but I think Henley and Frey together were the essence of the Eagles.
No, Glenn Frey was not the most important member of the Eagles because every member of the band made up the band's unique sound. To say that Frey was the most important would be to say that any one of the Beach Boys was the equivalent of the entire ensemble. The Eagles were an ensemble cast; that is, they only sounded great because they were all together. We remember them as a band, not as soloists.