I think a more telling reason may be the Reagan Democrats abandoned the GOP ... or should I say the GOP abandoned them.
Since you believe social conservatism was our downfall, I appreciate it if you would tell us what you think the GOP should stand for.
Opposition to social conservatism, or rather successful association of incumbent Republicans with it, was a key reason for GOP losses in the North East, not necessarily anywhere else. However, GOP wooing of blue-collar Reagan Democrats with promises of social conservatism is starting to badly hurt the party among libertarian conservatives. When at the same the Democrats have begun to diffuse the 'culture war' issues by running social conservatives in these districts, I see bad times ahead for the Republicans.
IMHO, the Republicans should embrace old-fashioned Main Street conservatism with emphasis on moderate, small enterprise free-market economics, positive family values conservatism and a realist foreign policy.