One subject that comes up very often in discussing GURPS is the issues with GURPS Magic. GURPS Magic for 4e is basically the same system as it's been since the inception of the magic system in GURPS.
It was revised for 4e, but mostly it seems to have been done with an eye towards staying true to the wording of the original book (written by Steve Jackson himself) than to a full shakeup and re-write based on 4th edition rules. It's a good system, but it's showing its age as the underlying system has made some changes and shook up some basic assumptions.
So there are a lot of legacy weirdnesses in it, things that were done one way in 1-3e but differently in 4e, lots of little places that 4e has a better way to do it, and spells that just have balance issues specific to where they were introduced.
Even casual observers will note that I'm revising the book myself, spell by spell, for my DF game.
So why not revise the whole book, for everyone? Or at least propose doing so to SJG?
I've considered it, but it's a tough sell.
Basically, because of how often the discussion comes up. It's a snake-pit of potential issues.
Play balance is a big concern. Trying to balance it against, say, RPM, spells-as-powers, technology, advantages, skills, powers, imbuements - it's tough. Now try to do that across all genres.
Not only that, but a complete revision would require a complete shakeup of the system, a large playtest (potentially, anyway - one would be demanded, even if "large playtest" isn't how things get done nowadays), and a lot of cross-referencing to ensure it all works out.
From a financial perspective, it would be a huge amount of re-use text and the royalties on a sold copy would be pretty small. So as an author I think - lots of work, lots of potentially unhappy people who don't like how I did it, and a small payout. So that makes it tough.
Revising GURPS Magic piecemeal, for my own purposes, is a lot smaller and enjoyable of a project. Sort of like Wizardry Refined, from DFIII, which just nails down what is needed to change to make it fit in the parameters of Dungeon Fantasy, the GURPS line.
Plus, if I do it myself, for myself, a lot of things are simplified.
The number of stakeholders? Small. Just me, primarily, and my players. Playtesting is limited to my table and my approach, so it's narrowly focused on making the game play the way we find fun. Even if our solutions are seen as inadequate or too severe for others, if they suit us, we're all good. It doesn't matter how broken our magic is, if it's what we like and want.
Campaign focus? I've got a very specific campaign going with specific ideas of what's appropriate to include in it. I can make rulings that violate the wording of spells if that fits the game's approach.
Game Balance? I don't need to worry about larger game balance. We have no worries about game balance outside of Dungeon Fantasy at the moment. If we change to a full-fledged fantasy game some other time, well, we'll just modify the spells again to make them fit that.
Deadlines? None. I can literally wait until a spell is used in play to decide to change it. That means it's a series of very small changes instead of a big project.
So that's basically why - revising the whole book would be a huge project subject to a lot of scrutiny and an enormous variety of different play styles and individual tastes. Nothing I do would satisfy everyone, and it sucks to hear a lot of criticism that boils down to "that's not the way I would have done it" but couched as "you did it wrong."
I'd consider doing it if asked - I'd probably take it on. But it's a place where everyone has a different idea of what "GURPS Magic Revised" would really be. It's not even just a question of people agreed on what is needed and disagreeing how it is to be done, but basically disagreeing on what is needed and how to do that. So for the time being, I'm satisfied I'm doing what I need done for myself and my players. Maybe what I write on my blog will someday provide a basis to do it for real, maybe not. In the meantime, enjoy it and use it if my changes also suit your games.