I'm principally a military engineer, for which reason (among others) my thinking tends in a military direction on susceptible subjects. Politics being the pursuit of power over others without the overt use of force, political philosophy qualifies as such.
Tactical analysis of ground-war situations seeks to discriminate between defensible and indefensible positions. The infantry can't be on the move all the time; when it's not, the positions it seeks to hold must be defensible, or it will be assaulted and possibly overrun. Though this sort of consideration is less emphasized in modern military studies, it retains a certain fascination for military historians, particularly those who focus on World War I.
One of the lessons of World War I is of the danger of salients to the side that holds them. A salient is a distinct forward protrusion in an otherwise smooth defensive line. Unless the natural features of the terrain dictate otherwise, such a bulge tempts a two-pronged converging assault -- "pinching the salient" -- to create a breakthrough. Such assaults were several times critical to events on the Western Front. The sole effective counteraction is to withdraw from the salient, smoothing the line to a uniform defensibility.
American conservatives, whose natural inclination is to defend that which they consider good, have several times in the past century tied themselves to positions on specific issues that had become indefensible because of larger cultural and technological changes. In sober truth, the larger changes have sometimes been deplorable, but such things are not easily reversed, and their effects on the enforceability of certain kinds of laws must be respected. For example, the ubiquity of the automobile has indirectly made laws against adultery, which at one time was a felony in every state, completely unenforceable. Changes in popular attitudes toward sexual pleasure have similarly vitiated the laws against (consensual) sodomy. Changes in popular attitudes toward intoxication have eliminated all serious possibility of enforcing the many laws about drug use. The list could be extended, but the point has been made.
When William F. Buckley defined the conservative as "one who stands athwart the gates of history crying 'Stop,'" he was principally thinking of the Communist tide and the seemingly inexorable advance of statist impositions through America's free-market economy, but topics such as popular sexual morality, drug use, and gambling were undoubtedly part of his concerns as well. During the decades immediately after World War II, the usual response to conservative plaints was to ignore them. Politically, intellectually, and socially, statist liberals were in the power seats. After the New Deal years, they appeared to be cemented into them. Even self-nominated conservatives such as Dwight D. Eisenhower were well disposed, in practical terms, toward the statist trend.
The conservative dilemma of those years was that not every position we wished to defend was defensible. Statist intrusions on the economy could be fought, though we did a poor job of it. The cultural milieu was a tougher nut. In time, technological advances plus the perfusion of American culture by hedonistic assumptions had made State enforcement of sexual and self-abuse morals, among others, impossible -- even self-defeating.
Many conservatives lament the surrender of those positions. Some of them have good reasons, too: many of the fruits of the Sexual Revolution, in particular, have left a bitter taste. But given the enveloping techno-cultural environment, such things are political salients whose defense is impossible. Stubbornness about them exposes conservatism to great damage with no practical prospect of gain.
The most recent crop of conservative thinkers and pundits have dramatically de-emphasized old-style "State moral conservatism," which the past century's technological and cultural changes have so greatly undermined. Most of these voices are moderately to strongly in favor of decriminalizing drug use; they have little to say about gambling or premarital sex. From a political perspective, this is to the good, and not only for tactical reasons. To harp on such things made their predecessors look unattractively priggish, which weakened their ability to reach the broad national audience on subjects about which it was still reachable.
None of this should be taken to imply that the older "moral conservatism," shorn of its explicitly political aspects, was in any sense wrong. It had become unenforceable -- indefensible -- in a practical sense. Doggedness about it, even when conservatives are in power, would require the weakening or outright retraction of Constitutionally guaranteed rights of great importance, but would not materially improve the chances of success. It would also drain the vitality from initiatives toward greater economic liberty premised on those rights.
Conservatives have begun to learn to beware the policy salient and concentrate on the stronghold of defensible principles. More is necessary, but well begun is half done.