What is it with mage items?

Why are mage items so broken right now? They're all either hyper offensive for no reason, or give the same defensive stats that a tank item gives in either health or armor/mr. 2500g Gives a decent chunk of ap, solid hp stats, AND cool down reduction (because if you don't have 40% cdr you're basically trolling) as well as a great active to help you A) Clear a wave B) Close a gap C) More damage for your already high burst 3200g An insane amount of ap. But then you see the cdr (funny 40% cdr joke haha) AND the mana so you can spam out your abilities more. Not to mention the passive combined with a single spell could half you. 3600g Why does an item give this much ap? Why does it also boost ALL ap by not 10%, not 20%, but 40%? 2900g Hey there enemy AD champions. I heard you were having fun so I built this item. Not only do I get a good amount of ap, but I also get armor so you do less damage to me. Oh AND you have the ability to burst me? Hahaha, no I'll just press 2 every time you have the ability to one shot me. And as a spit in your face I get cdr. 3000g Oh boy a very unique idea, lets give an AP item, but it ALSO gives health. And it affects the effectiveness of their healing. AND it gives pen in case you wanted to try and play the game by building mr.

Alright, fine fine, maybe when you compare them to other items mage items are ok I guess, reasonably priced and a good justification for all the stats they give right? 3733g The bread and butter for most AD champs. Costs almost as much as a RDC. Jack of all trades item with very solid passives. Probably the only item that compares to mage items. 2900g Gives an ok amount of AD and gives some nice lethality, fairly cheap. Active lets you run a bit faster for a tiny bit so it's not that bad. I mean mage items give more stats both offensive and defensive for the same price if not lower but hey it's so they can't get burst right? 3400g The "zhonyas" for ad champions. Except it costs 500g more. And gives less defensive stats. And everyone can buy the main reason to buy it for 1300g, while also being able to use it more than once. And you can also take cleanse so you don't have to sacrifice space for an item as a mage. But that's ok, that lifesteal will help you get burst .5 seconds slower! Hopefully! 2800g The anti healing for AD. Gives armor pen just like its AP counterpart. Costs 200g less. But it doesn't give really offensive stats and a ton of health so you can't get bursted. It's cause the 200g I promise 3250g The item you get against AP champs. Gives a solid shield. That you don't choose when it activates. Also you'd prob get burst through it all cause you only have like 1800 hp.

Bottom line is, why can a mage be dealing more damage than me, who bought nothing but lethality and armor pen items, burst me just as fast if not faster than I can burst them while also being somewhat safe doing so, run around with almost double my HP, have cdr in their hyper offensive/defensive items for no reason, and pay less for their great items? Don't worry though, maybe soon we can get AD zhonyas for 4000g, and a very good 40ad with it!