After a bit of research it seems quite possible that 8Gb of unified memory will impose future problems for the SSD, especially on base configurations. Its comparatively early days for Apple silicon and time will tell if the SSD's fail earlier than expected. Less RAM especially if Apple has its target set on Games and where many software producers already spec more than 8Gb. may result in SSD failures earlier so a good reason to have a 16Gb base soon.
Quite some ago an article in Macworld expressed concern at the SSD on M1: "Recent reports have shown that some users of M1 Macs are experiencing what they feel is unreasonable, excessive usage of the SSD. One in particular showed
15TB written in two months. That’s quite a bit, and almost certainly due to swapping main memory to the SSD."