Why does Zhonyas Hourglass last so damn long?
Seriously, items like Zhonyas are bought, not because you are against an AD mid laner, not because you want to ignore someone's highest damage ability (other than Death Mark) but because you just want to stay there and wait for you cooldowns to come back up.
Why is that a thing?
You made Sivir's spellshield a 1 second up time or something, why not do the same to this item?
I'm sure when the Zhonyas Ring was designed back then, it wasn't created with the purpose of letting medium cooldown hard hitting mages like Orianna or Xerath get 1 more spell rotation before dying if they missplayed terribly, it was created with the purpose of letting mages having a small time frame where they could dodge eachothers ultimates and therefor, avoid being destroyed in 1 rotation. (Annie, Brand, Veigar were pretty contested mid laners after the AD Mid "meta" fell off)