Too many abbreviations and not enough capitalization or punctuation.
I think im one of the few mages still playing arcane with 3.1 and heres the reason:
1.) There are fights like Malygos, where u get dmgamplifier, these fights depend on good burst in short times and arcane was ALWAYS on top @ Malygos. (By on top i mean 1000-1500 dps ahead)
2.) The threadeduction of the firespec is a joke. Taking into account that (at least in my guild) most of the ecounter will get tanked by deathknights, which build up the least threat of all tanks your going to stop your dmg for threat ALOT. Thinking about the T8pc4-bonus this even gets worse. 2 crits in a row. lb with glyph maybe just ending and crit for 4-5k, the one fireball which you were casting while hotstreak procced (crit for ~50%) + the pyroblast which you can cast 2 times in a row if t8 proccs... now just think about standing in the Shadow Crash of General Vezax.... And thats someting that happens REALLY often to me. There is no way you wont going to pull aggro or go invis/stop dmg to dont, which makes you loose a lot of dmg, while arcane is pulling ahead with 40% threatreduce and fullburst in this scenario.
3.) on Ptr i started icy veins a bit later to evo with the last tick of hero+icy veins, which lets you fight at least 4 minutes without any thoughts about fuckin up an evo.