[WorldMaker]

SLAAC isn't something that is an inevitable consequence of increasing address size, it's something that is a useful advantage of increasing address size. Almost no one had big enough blocks in IPv4 where "just choose a random address and as long as no else seems to be currently claiming it it is yours" was a viable strategy for assigning an address.

There are some nice benefits of SLAAC over DHCP such as modest privacy: if device addresses are randomized they become harder to guess/scan; if there's not a central server with a registration list of every device even more so (the first S, Stateless). That's a great potential win for general consumers and a far better privacy strategy than NAT44 accidental (and somewhat broken) privacy screening. It's at odds with corporate device management strategies where top-down assignment "needs to be the rule" and device privacy is potentially a risk, but that doesn't make SLAAC a bad idea as it just increases the obvious realization that consumer needs and big corporate needs are both very different styles of sub-networks of the internet and they are conflicting a bit. (Also those conflicting interests are why consumer equipment is leading the vanguard to IPv6 and corporate equipment is languishing behind in command-and-control IPv4 enclaves.)