It’s classic “tick-tock” strategy. With such a massive internal change, with lots of potential first-generation issues, it stresses the organisation to also revitalise the outside. Once Apple Silicon is settled in, an update to the outside with minor changes to internals will arrive.
It’s clear to me this is the first of two chips. This one for all the low end, then next year a higher end one for 16” Macbook Pro and iMac, with more RAM, i/o etc. Mac Pro will either get that or wait for next gen in 2022. I think the distinction between chips vs computer model will be more clear in the future. This was just the start. Two years from now, this lineup will kick ass. Right now the transition has started, so there will be weird things about the lineup.
Personally I am still hoping for an Apple TV-sized M1 Mac. Seems to be viable to do Macbook Air performance in that form factor.