The ideology of the "murder hobo" is as much out of apathy as it is poor role playing on the part of PCs. Using violence as an ends to a means is simply easier, more often then not, then entering into negotiations with sociopath entities intent on ending all intelligent life, or whatever there motivations may be.
Its also a shorthand for GMs. While most have the intent to develop overarching plot akin to Game of Thrones, with threads so thick it would an excellent topping on toast, or emphasizing immersion and actual character development beyond mere level acquisition and "looting", the point is it can be quicker to develop the generic "swing your sword at these other people who squat in dark, nasty places" crawl, particularly for inexperienced GMs unprepared for derailment or even experienced table toppers who need something on the fly.
Now I'm not saying murder hobo is a play style that should be emphasized, celebrated, or turned into a legitimate business venture. Killing everything in your path limits potential in a campaign and leaves only Nero playing his violin while Rome burns around him. But to completely excise the idea of killing things and looting there stuff is tantamount to removing one of the founding concepts of table topping itself.
That's why you have to strike a balance in different playstles