I like that bucklers are in the game, and that they are available to low-level bandit thugs, but I have to say I never use them myself (except perhaps for the very first battle of a new company, when the local market doesn’t have enough round shields).
One possible niche they could fill could be as an allowed off-hand item of equipment for battle brothers with the Nimble perk. Such a change would keep my guys in “The Artful Dodgers” happy while they patiently wait for new unique/legendary Saxes to make an appearance ;-)