So incorporating Type C right now feels like an interim solution and a half measure, at best, with a limited lifespan and none of the improvements that it's purported to include.
Does that seem worth it?
I'm just a layperson but it seems worth it to me, given that the M1 is updated somewhat frequently anyway (5 revisions in 5-6 years?). Unless there is a significant cost to adding a Type-C port, why not update it in the meantime?
It could still be years before motherboards change the USB header. And even when a new header comes out, it could take 1-2 years before all motherboard manufacturer's switch over anyway, which gives a fair amount of time to consider a revision. The M1 could have supported basic front USB C in the meantime and made some extra sales from its inclusion.
Personally, I like how there are a couple cases now with front USB A and C ports.