They’re not angry, it just seems that way.
It comes from the mixed Irish and Italian ancestry 99.9 % of them share.
When West Virginians speak, at first one thinks they’re angry. Then, the animated pseudo-angriness wears off and evolves into a long drawl, gets slower and slower, until it finally ends in a series of grunts, uh-huhs, and indescribable noises most associate with Cro-Magnon at Thanksgiving.
For example: picture two mountain men talking by a pick-up truck.
Mm1: (in a loud voice) “YEP. Me and the little woman are gonna go to town and see that new SEUSS movie. Ya know. One about that HORTON fellow. HOOTIN’ HORTON hears WHOs. I mean, Harried Horton hears hooters hootin’. (voice gets lower) Err, Hort and Harry hears a hootin’. . .or hears a hooter. . .no. . .that’s uh. . .ah. . .heck. Ya know. . .one bout’ them hootin’ who’s and Horton hearing. . .uh. . .hearing . . hootin’ hooters. . .or something ahootin’ and ahollerin’. . . .down town. . . .and. . .and. . .yeah. . .gonna watch Horton. . . .uh-huh. . . . . . . .yeah. . . . . . . s’whut we’re gonna do. . . .see H. . . . . . ummm. . .