Those points aren't even connected, really. You really want to have a discussion, well what am I supposed to say an argument like that? If I were to embrace logic, I'd give you a counter example. Mage's do 100% magical damage, so they should have terrible mobility too. Heh.
Mages do next to no damage when you focus them, good example.
+his points does connect because it really doesn't matter who you go on. A DK somehow manages to peel you ? (let's say HoF got dispelled).. just switch to him and take away half his life in 2 globals because your melee damage is more magic than melee.
If a mage and a rogue are on you, there is only one weakness which I already mentioned, your survivability. Nothing stops you from going onto the rogue and almost two-shotting him.
Someone saying the BURST of rets is below DK's and hunter's burst damage is quite retarded. DKs and hunters do have better sustained damage (especially DKs, hunters actually just have a more steady flow on damage but not better sustained) but their potential burst is quite a bit lower.
I advise you to just watch that paladin's stream http://de.xfire.com/live_video/euneek/
which is the double healer team on the PTR, and you will see people loling at the ret's burst every game. Because it really is ridiculous.
On top of that ridiculous burst they kill dk and warlock pets in a very few seconds, 13k damage in two globals without white damage is really fun.