If it’s only slightly. It doesn’t make a difference. It should change greatly if the routes had an actual effect on the story.
While in general I agree with consensus of how the individual routes of CLANNAD and Little Busters are important to the main story, I would also argue that Rewrite’s routes are kinda necessary too. (Rewrite spoilers below)
To me, Rewrite is about different perspectives, and how those perspectives affect one’s actions, with the central argument being based on the perspectives of Gaia and Guardian. Now story wise I won’t deny that many of the side routes don’t have that much of an impact on the end results, but they do have some. During Moon, Kotarou remembers all the possible routes that he took, and that affects his interactions with Kagari. One could argue that Kagari would have made Terra happen anyway regardless of Kotauou’s actions, but there’s really not much supporting that.
There’s also the consideration of the reader. To me, Terra is about Kotauou looking at both the different perspectives within the argument, and deciding to accept them both so that he can create happy memories for Kagari. It wouldn’t make sense to suddenly present that without showing the different perspectives and mentalities of Gaia and Guardian beforehand. So even if plot wise there’s not that much reason to do the previous routes, thematically it makes sense that all those different routes are there because they are used to show those different perspectives.
This echoes my feelings too. I can see how the alternative routes in AIR could be considered as insignificant deviations since the “good” ends have no impact on the true end, but each of them does add meaningfully as @DaBackpack says to the narrative ( yes even Kano’s albeit a weak route and Minagi being overlong).
However you could of course - if the VN allowed - finish AIR without completing those routes without missing anything truly significant in terms of the whole story and the impact might even not be weakened. Although I am glad of the existence of the routes, Kano and Minagi do feel like the closest thing in a Key VN I have completed to dating sim territory.
Then again, I have ploughed my way through tons of RPGs with the inevitable numerous L1 “kill the rats / goblins”, FedEx fetch and carry sidequests to level up and maybe a tolerance of this is more ingrained…
So the word for this thread is [Diegetic]. If something is diegetic that means it exists within the universe of the story. Most of the time this word is used to describe music in film. There isn’t actually a full storm trooper orchestra playing Imperial March wherever Darth Vader goes, but the music in the cantina in Mos Eisley is performed by an in-universe band etc.
There’s lots of things in VNs that can be diegetic or non-diegetic, but this thread is basically about whether the muli-route structure of the games is diegetic. Multiple routes is just an industry standard, and players expect that from galge regardless if they’re diegetic or non-diegetic.
In Key games routes are diegetic most of the time because of various concepts they’ve come up with over the years. I probably wouldn’t say routes are diegetic in Air since I don’t recall the text ever directing your attention to it, but there is the thing with the bird; Air doesn’t throw you many bones. Clannad has a very brief comment about what makes the routes diegetic towards the end. Since Clannad though, they committed hard to making all routes diegetic, coming up with way more elaborate shenanigans.
Those later ones are fun and all, but I feel it’s starting to restrict the storytelling. Characters being stuck in a time-loop/groundhog day scenario has become oh so very common. If we could just dial it back a bit?