What is this obsession with doubling stats in buffs?

Brand's Ability power needed fine-tuning because DFT was removed, thats understandable.

But this buff took the DoT value from 2/4/6% Max HP based on stacks to 4/8/12% based on stacks. I don't know about you, but I think putting down an additional 12% max health damage with a kit that already has a high damage value (remember, the burst damage part of the Ability was not modified or removed) seems like a lot for one mage carry, especially when in the same breath they nerfed part of the damage output of another mage carry in Heimerdinger.

Can we put more effort into long-term damage theory instead of just doubling "small and weak" numbers? I feel like we can make 3/6/9% based on stacks work just fine, especially with all the runes that fit mages so well at the moment.