1. I disagree with the statement that fire and lightning are the best attacks. Earth (Hurl Boulder) is the most mana efficient from a pure attack dice standpoint, and it cannot be resisted by Elemental Cloak.
2. Iron Golems on guard are extremely devastating vs aggro because they have so much armor and attack dice. Nonflying aggro creatures will be quickly smashed by the golem, and flying creatures cannot get around his Guard without an Elusive. If you cannot get an Elusive flyer (such as Lord of Fire with Mongoose), you need some other way to deal with the Golem.
3. Arc Lightning is insanely mana efficient against iron golems, not just for damage but for rolling stun/daze. Teleports can move the iron golem away, but are very expensive for an aggro build.
4. When running an aggro build it is 100% certain that you will put your own Mage within range of your opponents attacks. This means you have to be very careful not to let your Mage die. Running an aggro Beatdown with only offensive enchantments means that your opponent may be able to kill your Mage before you kill his. Often times, an extremely offensive aggro deck actually works better when you throw on a 6-mana armor early. (Dragonscale or storm drake)
1. Even without a Ring, Fireball has a 75% chance to roll just as many dice as Hurl Boulder, but with a good chance to roll more, with the added caveat that each die past the first 6 rolls unavoidable critical damage. With a Ring, Fireball is obviously the better choice, whereas Earth attacks have no such ring. Sure you could introduce armor, but I already mentioned how armor plays into the picture. Plus, earth attacks don't have efficient low cost attacks like Fire or Lightning does; you're committing a lot of mana when you use any Earth attack, so it really needs to pay off or you could be set back more than you'd like mana-wise.
2. Iron Golem guards aren't too big of a deal. Any aggro book worth its salt is going to have Mongoose Agility or Evade or some combination with Elusive creatures as you imply. A piece of armor and an Agony is also a pretty cost-efficient way to deal with them, since they don't have any piercing and can't effectively pursue you.
3. Yup, I mention lightning being good exactly in that situation. And I disagree about Teleport; the lowest channeling a mage can have is 9, and if you teleport a Golem 2 zones away (6 mana), that's a good way to buy yourself 3 turns of that Golem being pretty useless, so you're at most spending one turn of mana to buy quite a long time. Teleport is also very useful for efficiently removing conjurations that Restrain such as Tanglevine and Quicksand, which are in my opinion, much more problematic for aggro builds.
4. Yes, it is a concern that your mage is going to take a beating, but that's why I recommend the Vampiric trait as a way to heal your damage as you apply pressure. It ensures that you either get much more mileage than a simple healing spell, or that your opponent uses actions dispelling it. In either case, you're going to be staying alive much easier.
I do understand your point that Aggro strategies need to provide disruption, and I agree. I myself play the Warlock a lot, and he leans very aggro-control. I'll be talking about aggro-combo and aggro-control very soon, and I think that will address the concerns you're having. Aggro cannot usually be executed very effectively without some kind of disruption, like Mind Shields, Nullifies, curses, Jinxes, etc. Some books will have more disruption, like the Warlock, and some will have less, like the Beastmaster.