Because the first wave of M1 devices - the Air, 13" MBP and Mini - are now 18 months old and ripe for an update. OTOH, if it follows the M1 pattern, the M2 Pro/Max/Ultra won't follow for some time yet, and the MP will need at least an Ultra.
I really need to replace my personal 2013 rMBP because of excessive battery swelling. I'm not sure, but I imagine it's starting to become a safety hazard and I don't really want to accidentally set my house on fire.
The MacBook Air is more than enough for my needs but I just wouldn't buy it at this point. As you say it's 18 months old and it either requires an update or a lower price, both of which would work for me.
I'm hoping for an announcement today because then I can at least plan what to do next. It's not a machine I really need on a daily basis, so I can wait, but it's getting tiresome.