The big problem we have when attempting to come up with a solution to the Magic Problem is that we(*) work within a box. There are too many things that get in the way of fixing the problem because we cannot seem to look at it objectively.
(Disclaimer: When I say we, I mean us internet forum gamer sorts collectively. This comments may or may not apply to you particularly, so take no offense. It's an overall thing)

First off, most cannot help but consider how a given change would affect their army. This is bad. As soon as someone starts complaining about how a given change would damage the way they play, their advice and opinion become largely useless. We're all, at some point, guilty of this.

Ultimately, it's impossible to solve the problems with something so broad as magic without pissing off people. It WILL affect game balance. Not necessarily negatively overall, but it will (relatively) strengthen some armies and weaken others. This applies to a good many other changes to the game, too. It's just a reality. Remember how many people raged at the beginning of 6th edition, about how their army was so horribly nerfed under the new rules? It worked out in the end, though.

So, a given change negatively impacts your army? To bad. It's not necessarily a problem with the suggested change, rather it's a problem with your army that you'll just have to cope with until GW gets around to updating your army book to work better under the new rules. That's going to happen no matter what.

Further, even those who play a large number of armies (and thus are less directly impacted by a change that just nerfs one or two armies) still have some measure of problems. We play the game, and get used to playing in certain ways. Some things that work now, tactics developed over time and with lots of hard work, just won't work later. New tactics, new playing styles will need to be developed.

But wait! There's more! We've all got different ideas, visions, of how the game should be. And, from person to person, these ideas differ GREATLY. How can we possibly come to a consensus on how to fix the game when we can't even agree on what would constitute fixed?

Well, I've come to realise that there is certainly some point to having the games designers be designers first, players second (or even not at all). Someone with no vested interest at all is going to have a much easier time making tough decisions (as they won't be tough at all) about changes that will fundamentally affect armies and how the game is played.

So, where am I going with this rambling quasi rant?

This is it in a nutshell:

The best procedure I can think of for us to seriously discuss ways to improve the magic system is as follows. First, we need to hammer out a mission statement of sorts, exactly what we wish to achieve. Not the method of the change, but rather the results(as specific as possible, not generalities). We can hammer out the pros and cons of the various results then.

Once we've settled on a given set of specific results that we wish to achieve, THEN we can look into how to achieve those results. People disagreeing with the results themselves can take their posts elsewhere, as time for that has come and gone. Delete the posts. They're non-productive and spammy, and just result in the thread getting hyjacked into arguing WHY we are looking for ways to achieve said results. Simply work on methods to achieve those specific results, without fear of causing some measure of imbalance considering the current crop of army books, as they will be adapted as we go along. We can have several of these threads running simultaneously, if there are a couple "result sets" that people are interested in.

Without keeping to a rigid procedure such as what I've discussed above, I don't think we'll ever be able to have a terribly productive discussion on how to actually fix the magic system.