I wouldn't say the author forgot. It's mainly due to the addition of more in-depth side characters/stories and the consequences of the end of Part 1. The end result of Part 1 basically made Asuna put an almost full stop to her IRL progression with Inoda, because she's trying to not let things get out of hand. This ends up meaning the only place to corrupt her ends up unfortunately being in FOG.
If you think the story reasons don't make sense, then the other reason is that Fujino is adding more moving parts to their updates. Those moving parts are the side characters/stories. Since Suguha, Sinon, Liz, Kyouko, and Alice's progression ends up either directly or indirectly affecting Inoda, Asuna, and Kirito's relationship with each other, it ends up making the updates having to hyper focus somewhere. That somewhere ends up being FOG probably due to how Part 1 ends. Basically it's possible Fujino could have added a bunch of mini/minor scenes IRL but to be fair those scenes wouldn't have progressed to the point of intercourse and be a repeat of a lot of scenes from Part 1.
The good news however is that IRL progression should hopefully start happening in a few more updates. Depending on how this upcoming update goes, we can probably gauge what the next one will be like. If Fujino mentions the next update will focus on battle updates, then it's probably likely the one right after will finally show significant IRL progression. Asuna should probably be more than corrupted/thirsty for more virtual sex that it'll translate into IRL in probably 3 updates max. That's definitely a long time, but 3 is better than waiting for 8 more I guess. I don't even know if it'll be in 3 updates, that's just my guess with how I think the progression of events is going. But also on the flip side IRL progression could easily start ramping up on the end of November update (if Fujino releases at the end of November) since Asuna theoretically should be corrupted enough to desire some relief to her sexual frustrations IRL.
You guys got this; you just gotta wait a little more.