@sozobe,
My original assertion was that the media is deliberately trying to paint a picture of a disinterested Republican electorate. Despite your recent calculations I continue to hold this opinion. I've explained why below but you may not care to read the details.
In any case, even if assume that the media is right and that Republicans are to some extent disinterested in the primaries, that doesn't mean they will be disinterested in the general election.
We have had only two primaries thus far and there is already a general sense that Romney's nomination is inevitable. With the exception of Ron Paul, it's pretty clear that none of the other candidates can attract a sustainable following.
Someone might stay away from a primary because they feel Romney has it sewed up or there is no candidate that enthuses them, but that certainly doesn't mean that they will stay away from the general election.
Beating Obama was far and away the primary concern for NH primary voters. It certainly wasn't "Seeing Mitt Romney lead the country," or "Putting a conservative in charge." It would be better if there was a Republican candidate who fired up folks the way Obama did in 2008, but it won't prove necessary. In a sense Obama will be firing people up again in 2012, but they will be the ones who vote for anybody but him.
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Assuming the 37% figure for 2008's independents/undeclared is correct, then there was an 8 point increase in independent participation in 2012 over 2008.
(Considering your source for this figure reported a drop off in Republican participation of 40%, it can't be considered authoritative)
The total number of participants increased from 2008 to 2012 by 10,522 voters or 4.5%
If your premise is correct, that Republican participation in 2012 waned from 2008 we must conclude that non-Republican participation increased.
Does that make sense to you?
You are making the case that Republican interest is down from 2008, but even if this is the case why would non-Republican interest be up?
Republicans are not excited by the 2012 candidates but non-Republicans are?
Again, assuming that your figure of 37% is correct, it seems more likely that the explanation is that the number of registered Republicans who shifted to a registered status of Independent increased in the last four years.
I don't know why people feel the need to change their registration status, but many do. However, if you change from Republican to Independent, it is most likely that you continue to lean right, just as those who switch from Democrat to Independent are most likely to continue to lean left.
Therefore there is a fair argument to be made that interest in the 2012 Republican primary by right leaning individuals remained about the same or increased since 2008.
In any case to claim that there was a 40% drop-off in Republican participation is ludicrous and would have been so even at the point when 87% of precincts had reported.
This is evidence that, at least, one media source was eager to report that Republican interest had waned, irrespective of the actual numbers. They were not alone.
Two additional points worth noting are:
1) The vote count is a real number, the party affiliation percentages are based on exit polls, not actual counts.
2) It is widely accepted that primary voter participation in a year when only one party is seeking to anoint a candidate drops.