Really for most group encounters EQ worked the same way. Clerics definitely healed the best, but 2 druids was usually good enough, or a shaman slowing the mobs, shit I've healed groups with a necro before. Warriors, SKs, Paladins, and even rangers or monks could tank most "group" content in OG EQ. For CC an enchanter or bard was really sexy, but Clerics, Rangers, Shaman, Druids, Wizards, Necros, Paladins all had alternatives.
EQ classes and to some extent VG classes were way more specialized than what you find in say WoW. (Though in VG healers just were a bit ridiculous. I don't know how many groups I main healed, main tanked, main pulled simultaneously on my Cleric.)
The problem is that in EQ you had "bests". Warriors tanked the best, Clerics healed the best, Echanters mezzed the best, Shaman slowed the best, Rogues/Monks/Wizards did the best DPS in most situations. Necros/Mages/Druids soloed the best. WHATEVER. In WoW the goal would be for Warrior/SK/Paladin to tank exactly equal. Rogue/Monk/Ranger/Wizard/Mage/Necro/Enchanter would do exactly the same DPS. Cleric/Druid/Shaman would heal exactly as well as each other. Etc. In EQ it was okay for Warriors to tank better because SK had all these cool spells that may not have made up the difference in a min/max situation but definitely added some utility and fun factor. Clerics could heal better than druids because druids had snares and dots and ports and regen and thorns and other desirable things that still didn't make them as desirable as a cleric for healing but didn't leave them as anything but their own unique snowflake.
You get what I'm saying. If you want to min/max balance every single aspect of game play you will eventually end up with something bland. If druids can heal as well as clerics do clerics then get ports or does a new mechanic have to be designed to make clerics useful outside of healing now so they aren't vastly inferior to druids?