Along with several shōnen battle anime, Sword Art Online was instrumental in the increased popularity of anime. Said success even saw a growing amount of light novels taken out of Japan and localized in the West through the original source material of the series. Unfortunately, there's one medium that hasn't seen this same level of stardom when it comes to the otherworldly virtual realty franchise.
For a lot of anime franchises, they get their start as manga instead of light novels. That's not the case with Sword Art Online, with the manga being essentially a side project compared to the source material and the anime adaptation. This makes these projects incredibly overlooked, and prevents the series' hit performance in other mediums from being replicated in comic book form.
Sword Art Online's Manga Is the Franchise's Biggest Failure
The original Sword Art Online: Aincrad manga was serialized from 2010 to 2012 and comprised two volumes that adapted the "Aincrad Saga." There would be numerous manga in the series since then, from comedic 4koma comics to adaptations of other manga story arcs. Unfortunately, not all of these stories have been completed, something which was arguably impacted by the release schedule for the English versions of these books. While things eventually caught up between the countries, some of these SAO manga volumes would release in the West as much as two years after their original Japanese release. An example of this was the canceled Project Alicization manga, which only reached a one-year gap in regional releases for its final volume. There was also a huge gap in general for the release of certain subseries' volumes. For instance, Volume 3 of the manga Sword Art Online: Phantom Bullet came out in Japan in September 2016, but the next volume wasn't released until nearly six years later in February 2022.
Almost all of these manga have different creative teams, giving a lack of consistency between them. This isn't helped by the fact that some of them constantly rebrand without even finishing the new storyline being introduced. For instance, Canon of the Golden Rule was never completed, with the scant few manga volumes for the story likewise only available in Japan. Some of these ended due to quality and criticism, which says a lot given how controversial the franchise already is. The Sword Art Online: Ordinal Scale manga are also yet to be localized or even updated, with the latest volume coming out in May 2020. When added to the fact that none of the 4koma books have been released in English, it's noticeable that a huge swathe of the franchise's comics are simply not a priority.
Why Sword Art Online's Manga Series' Aren't A Major Draw for the Franchise
As mentioned, Sword Art Online didn't start out as a manga: instead, it was a web novel, then a potentially soon-to-conclude light novel before becoming an anime and a manga series. By the time the first manga had begun being compiled into tankobon volumes, the anime had already started airing. In 2013, the English dub was released and broadcast on Adult Swim, whereas the English version of the first manga didn't come to Western shelves until 2014. Said 2014 release was only a month before the release of the light novel that things were based on, and given that the anime had already hit the mainstream, this presented a huge issue, especially for fans outside Japan.
The Sword Art Online novels already presented the story from a purely textual basis. On the other hard, both the manga and the anime provided more visual mediums, but one is far superior to the other in most fans' eyes. If fans didn't want to read the story at all, it made more sense to simply watch the anime instead of reading the half visual/half text manga. On top of that, the manga for the main series didn't really add anything new to the mix, making the anime and the novels superior in one of two respects. The only truly vital project in this medium when it came to the main stories would be the manga adaptation of Sword Art Online: Progressive, which did a good job of handling the material while also switching things up by showcasing the story from the perspective of Asuna.
The increase in the Western releases for light novels and their audiobook adaptations has only helped to make the manga even more irrelevant in the eyes of fans across the world. It's quite strange given how popular the franchise is in other mediums, with even video games fittingly being produced for it. Despite its many issues, a lot of fans see the anime as their gateway to the series, with the light novel being either above or right below it in this regard, The biggest issue with the SAO manga is that they were simply released at the wrong time, especially for fans in the West. This has resulted in them being utterly irrelevant in the grand scheme of the franchise, especially since so many of these unfinished manga have already logged off.