I still have my 1, 2, 3 keys on the hotbar since ARR for old times sake, like a little memento.
Yes, there would be people who didn't care much about killing mobs in a certain order and used AoE's instead.
I remember I had to spam the cone AoE as a WAR to build aggro.
And with skills costing Stamina back then, making sure to keep aggro without a real Taunt skill (early on at least) meant that I spend a great time just building aggro to make sure no mob would break and attack someone else.
Which now when I'm saying this reminds me that the 1, 2, 3 was also helpful for the tank to make sure that people stayed on 1 enemy to not spread out the aggro, making it more difficult for the tank to manage the aggro & Stamina consumption.