Guild Perks were an addition in Cataclysm -- there were 25 different Perks and different levels to the Guild system, and it encouraged many people to skill and level after joining different guilds -- such as reducing durability loss, increasing reputation gains, increasing Honor and Justice Points, increasing skill traits and materials, and of course, Mass Resurrection.
https://wow.gamepedia.com/Guild_adva...vels_and_perks
Are most people happy that they are gone? Or do they want them to return in some way, shape or form? I must admit, I actually personally enjoyed them a lot when I was first invited to a guild, saw these dozens of passive bonuses, and made it feel like everyone part of the guild was contributing to each other's efforts, and had something just for being a member of the guild. They do not have to restore the old ones -- but adding new and more relevant and useful ones could turn out to be very interesting.