While I agree that a lottery/rotation system seems more
fair, it does have drawbacks. That small (population)
states like Iowa and NH go first means that candidates
must practice so-called "retail politics" -- meeting
lots of people face-to-face and having many small rallies
where they actually answer peoples' questions. Consider
what their campaigns would be like if California was the
first primary -- it would be mostly television/radio/print
advertisements. Holding events in major metro areas
like the SF Bay would be difficult and limited. Only a
very small percentage of the state's voters would get
a chance to evaluate a candidate in person. Whatever
else you say about them, people in Iowa & NH take their
role in vetting candidates very seriously.