I like the artwork for him and the design of 'Old fashioned Eastern European meets Asian Monk'. Perhaps as they said they looked at fighting games for inspiration they didnt want him too look at an obvious clone of the Virtua Fighter 5 character.
He's partially based on eastern European culture, so culturally speaking his beard makes sense. Also, 1) this is Diablo, and 2) this isn't a Korean MMORPG, therefore as few classes as possible should look like Zac Efron.
If you've never met a muscular dude with a shaved head and a full beard, then you're just not going to be able to comprehend the manliness and intimidation level that such a look brings to the table. He looks like someone who couldn't decide between Dhalsim and Zangief, so he just combined the two looks. No complaints here.