I thank you for your reply, Though I do have some questions. Was stacking critical more damaging than say.. stacking attack? I'd also like to note that I've seen a lot of people say that lightning bugs out in combination with RF skills, is that not a thing anymore? Last but not least, do you find Firestorm to do more damage than say.. Mark of the Rift?
I'll be honest with you - I've yet to play a mage that went down the +attack route, so I can't give you an accurate answer on that. I don't know an in-depth amount of information on the mathematics behind it all. All I know is, I crit and I crit often. 
I believe there is still some bugs regarding the Weakness status with Rift Mages, but because of the skills that I use it's non-consequential. I rely on Lightning Cage for increasing my DPS and my crowd control. I don't use, nor do I need, Pull of the Abyss, freezing, etc.
The only downside to the build, IMO, is that it's repetitive and doesn't require much strategy. Plant your large-radius Lightning Cage around the majority/all the enemies and just go all out offensive. Lightning Cage also prevents mages and demons from teleporting out the area, rogues in stealth often trip the boundaries and get pulled back to the center, etc. It's a very powerful and safe build that I've found exceptional in Nightmare mode.
As for Firestorm - I keep it there for personal satisfaction. I like being able to call it down whenever I'm in the mood to - generally on bosses.
However, if you want to play the part of Rift Mage, utilising their skills as well as the passives, I would suggest going down a slightly different route - utilise Pull of the Abyss and AoE skills to cause carnage for the enemy.