Both the code of Bushido and the less culturally specific "Texas Justice" mentioned in this article arose in similar circumstances -- cultures that are war-like, family-centric and deeply conservative. Bushido, however, likes to put on the face of self-censure, and therein lay the real difference.
Neither seppuku (suicide with a helper) nor harikari (the solo version) were matters of "killing yourself if you get super pissed and can't find anybody else to kill" (as per Real Ultimate Power). They were a means of averting the wrath of an indiscriminate government, which would punish your entire family if you failed to make up for your shame in the appropriate way. Of course, your family would not be happy about this -- the option of "do it yourself or your family gets it!" drives a wedge between the family and the individual, strengthening the position of the central government by a large margin.
With a government so strong that it can even make people kill themselves, who needs to go around enforcing one's honor by wildly killing people? The strength of the government encourages order, both discouraging revenge and the slights that lead to it. Disputes go through "official channels" and people have confidence in their resolution.
In lieu of "the rule of law", people are more inclined to take justice into their own hands. When there is no law to cover a certain trade or group, honor killing often reasserts itself. Consider Asian gang members in San Francisco who traffic in narcotics -- when one cheats another, they have no one to turn to for dispute resolution, so it's killing time!
So many things are bundled up in that article -- misogyny, honor killing, notions of honor, backwardness, privilege -- but it is important to acknowledge that "Texas Justice" (lolz) is present whenever the sheriff is absent, weak or corrupt. Take a bunch of "Enlightenment" people, put them out in the middle of nowhere with some guns and, voila, you've got Thar!