It's nice that people run in the room and scream "this is so stupid OP it is so broken why are people so dumb?!?!?!", so that we can confirm that nobody else thinks large shields are a 'must have'.
I'd say it's actually one of the more balanced, clever options: it has a very clear and tangible benefit in the right setup/situation, making it attractive to use, but at the same time it's not so much better than everything else that it's a default. (If only the same was true of, say, dual-wield vs. 2-handers.)
Edited by Tigranes, 14 June 2018 - 05:41 PM.