If 1981 is notable as the year the X-Men arguably grew into a franchise (I know not everyone agrees with me on this, but Dazzler counts, dammit!), and 1982 important for the publishing of Marvel Graphic Novel #4 and the first Wolverine mini-series (both extensions of Claremont's personal vision rather than simply Marvel expanding their reach), then 1983 is the year that the X-Books were finally solidly established as an ongoing concern, and Claremont ascended to the role of caretaker of Marvel's mutant population.
By the end of 1983 there were no fewer than four mutant-centric series in publication. Two were written by Claremont himself, a third was based on characters he created (Byrne's Alpha Flight) and a fourth concerned itself with a superheroine he so seamlessly wove into a 1980 issue of Uncanny X-Men that an awful lot of people mistakenly believed him to have created her, rather than simply introduced her to comic fans. On top of that, we saw the start of a second X-Men limited series (Majik: Storm and Illyana, which Abigail assures me gets better).
That was written by Claremont, of course, so at this point he's been responsible for taking the still-young X-Men relaunch and turning it into a smash hit, demonstrated how to put together a successful spin-off, provide the bedrock for two more, and provide templates for both the "important" one-shot and the limited series.
It's not just Claremont's recent work-load that suggests he's taken on a holistic role, though - a role that really no-one before him can really be said to have had. It's also expressed in his choice of stories. Just think about the ideas Claremont introduced into the Marvel Universe in 1982: Binary, the Brood and the Acanti, the revelation of Magneto's past and Wolverines Japanese connections, the Sidri and the Bamfs, and of course the New Mutants themselves. 1981 was even more full of new creations and concepts (the Morlocks, for one).
In 1983, though, there's a noticeable reduction in major new ideas. You've got Selene and Amara (and Nova Roma along with them), and you've got Maddie Pryor, and that's about it, despite Claremont having a whole extra comic to fit ideas into.
This isn't intended as a criticism, not at all. I think drawing on the Marvel Universe's past and extended cast of characters is almost always a good idea - provided of course that it's in the pursuit of a strong story, and not intended to be an end in itself - and in a situation where one's own slice of this giant sandbox is expanding rapidly, absorbing characters like Viper, the Silver Samurai, Henry Gyrich, or Team America (well, maybe not them...) strikes me as sound method for strengthening the franchise's foundation. So too does drawing from the book's own past, though of course this practice is fated to cause far more than its share of problems in the future.
For all that much of Claremont's material hasn't aged well, and tends to have jarring changes in tone that I can't believe weren't problematic at the time, this kind of top-down awareness of how to treat a multi-book concern always seemed to be one of his strengths. Not just in terms of the overall nature of his output, but also the clean distinctions made between titles. Compare the differences between UXM and NMU with, say, New Avengers and Mighty Avengers between the latter's debut and the conclusion of Secret Invasion. Whatever one's feelings regarding Brian Michael Bendis (and I'm a lover of that particular brand of Marmite, though perhaps that's helped by having read too little of the Avengers' previous adventures to be upset by the massive errors in characterisation others have accused him of making ), both those books mainly exist in order for two different groups of superheroes to talk a lot before they punch out some poorly-defined horde of mooks. There's nothing in either book that would feel out of place in the other.
UXM and NMU work somewhat differently. Whilst UXM gets ever darker (as evidenced by how Kitty seems more and more out of place), NMU begins as a far lighter read, interested in the unique behaviour of teenagers and how to extrapolate that to the super-powered, rather than struggling to protect a world that hates and fears them. Eventually, the idea that the new team only ever get into life-threatening scrapes entirely by accident will be dropped, but right now the difference between sending Wolverine and Storm to combat terrorists and sending the New Mutants to the Amazon in the hope of getting some R&R is noticeable. Looking at these two comics, along with the blood-stained Wolverine ongoing series and bonkers Excalibur when they appear a few years down the line, it's obvious Claremont - at least at this stage in his career - understood the need for clearly defined identities for each book, something that has often not been true in recent years.
In short, then, Claremont proved here that not only was he the right man for the job of building the X-Men into an international phenomenon, he was the right man to capitalise on that success by assembling and overseeing the franchise. Dazzler may be struggling, having gone bi-monthly and seeming to have lost its direction following Fingeroth's departure, and Byrne's Alpha Flight, whilst fun, has severe structural problems regarding its female cast that are more than a little worrying, the heart of these mutant books is entirely solid.
 That said, though, there was nothing in All-New X-Men that particularly bothered me, other than the fact that it's replacing a comic cancelled after a 37 year uninterrupted run for no good goddamn reason whatsoever.