Vitali just goes for maximum wear and tear, he doesn't even need finishing abilities. He just keeps pounding and pounding. Also it's just how his ugly style is. It's awkward but it's working.
He used to, that's how he built up the best KO ratio of all HW champs, but became more of an arm-puncher after suffering more injuries. He's deceptively fast with those well-timed left and right hand counters, at least was until recent fights, so he's not gonna go back for body power.
He would generate more power but that akward armpunching from crazy angles while moving back or in is what makes him effective(IMO). His opponents just seem befuddled.
If Vitali hit harder than Wlad, Lewis would have died. But that was post Byrd so your argument probably still stands. But Vitali doesn't have the one punch power that Wlad has, Vitali is pure accumulation, he also has fought worse opponents than Wlad. And Sam Peter was already ruined by the time he fought Vitali. He's just a different KO artist than Wlad is. Wlad does fewer punches, Vitali more.