I'm not certain what you mean by:
they nerfed our itemization a lot.
It seems to be the crux of your argument here, and I simply don't feel that it's the case. Many of the old AP items got revisited and given more impactful passives; Tear, Catalyst, Hextech Revolver and all of their associated upgrades are unquestionably better than before, the former two specifically for mana based mages. Abyssal Scepter and Zhonyas are both better for the addition of Cooldown Reduction to their stat profiles, even if they lose a little ability power.
The magic resistance on Specter's Cowl, Spirit Visage, and Guardian Angel have all been reduced. It's an indirect buff to mages.
Will of the Ancients was removed, but let's be honest, who was using it? Vlad, maybe Mordekaiser or Swain, and occasionally a handful of others as a situational item. The stat still exists, you can get it via runes and masteries, but such a large source being made unavialable means that champions that practically required the stat can now be buffed.
Maw of Malimortius is nothing new, and I don't see why people continually cite it as a problem for mages (though not you specifically). Maybe a change in playstyle to deal more consistent damage (which with the addition of more convenient CDR, shouldn't be hard) and be a little tankier (more hp on the new items) instead of going glass cannon every game is warranted.
A lot of mages were turned into something the whole community didn't want.
Bullshit. They spent months taking in feedback about what people loved about each of the "big 6". Considering the changes made, they listened pretty damn well. This has been the most open and up front set of reworks since the concept of a "rework" was first implemented.
I would rather they low-ball the numbers on these guys to begin with, like they have, then bring them up to speed with everyone else. The petty complaints I'm seeing around the boards boil down to:
"The Juggernauts and Marksmen were OP when they were released, why didn't you make the Mages OP on release RIOT? I want to steamroll everyone with the new abilities and items like I was back in the day! How dare you take a conservative approach to these reworks? How dare you try to avoid the mistakes of the past?"
It's ridiculous to think that the whole of RIOT, every single employee, is in on a conspiracy to elevate AD characters while suppressing AP characters. It's equally unreasonable to think that some of the older characters, not crafted with the same experience and thought displayed today, would need some of their more abusive characteristics tuned down or removed.
The general childish behavior behind the complaints is what bothers me. It shows no consideration for the other side of the issue and displays a willful ignorance of the subject matter. I've only seen a handful of useful complaint posts, expressing their frustration in a reasonable manner and providing solutions. Further, the comments follow the same quality, why should someone take the time to write out a well thought out post when few people bother to comment or vote on the topic, and those that do respond with effectively "Lol you're wrong.", no reasoning, no counterargument, nothing.
I can't say I'm surprised though, the format of the boards, effectively copy/pasted from Reddit, breeds this sort of behavior.