I do think the toleration for brushback pitches contributed to the strikeout rates as well. I think pitchers being able to brush hitters back and also the raising of the mound after 1961 meant a balance of power in favor of pitchers. That meant fewer walks in part because pitchers did not feel a need to be so careful - HRs were at natural levels minus some due to the advantage of pitchers, so they walked fewer and batters may also have known pitchers threw more strikes, so they swung more freely, again contributing to lower walk numbers and therefore lower OBP.
The 1990s instead was driven by the threat and the greater chance to hit a long ball - batters swung freely this time because three strikeouts and one 3-run homer was a good day (Adam Dunn), and pitchers walked more batters because of the danger of the long ball from first through 9th in the batting order. So, higher OBP.
If this hypothesis, admittedly idiosyncratic explanation of things, has some truth, then instead of OBP being an effective strategy for run production and success, it is instead a dependent variable, an effect, not a cause and so cannot really be taught or made into an alternative way to score runs, since it is largely the result of HR levels, which in turn are the result of pitcher-batter balance of power (raised mound in the 1960s, PEDs in the 1990s).
If so, then the idea that bunting, stealing, hit and run, are counter-productive may be true only for the high home run era of the 1990s, and not applicable to low OBP/HR eras when it can't be assumed that the next batter has as good a chance to end up on base or hit one out of the park as not and so should not waste their time bunting or have the bat taken out of their hands by the running game etc.
If this in turn were to turn out to be true, even if only in part, then the low run production may not only be the end of steroids - after all while low, run production WAS higher in the 1960s and 1970s than in the last 3-4 years - but be the application of an offensive strategy, learned only toward the end of the steroid era of high OBP instead of averages, the inside game and so on, which was applicable to that era because a batter at the plate was potentially more valuable than moving a runner over by running or bunting."The owl of Minerva take wing at dusk" wrote Hegel (he played third base for the Cubs in 19th century) meaning generals always plan for the last war, or rather human understanding always comes after the situation in which it could have best been applied. This may be the case today, and a return to classic baseball strategy, and a rejection of "Moneyball" techniques of station-to-station baseball may be in order.