I think the first batch of M1 macs should be seen as continuity machines, they made the processor the only differentiating factor in order to make the transition trivial for consumers.

About the sides, i was confused at first but I think the idea is that they will do what they did to the ipad. Compare the first ipad to the ipad pro, the pro lies flat on the table but the first one (and to some extent all ipads before the 2018 pro) has a curved bottom like a boat.