Well the Hammers of Sigmar are supposed to be generic and bland because they are the poster boys, and to GW's credit they haven't used Vandus and the other leaders of the Hammers that we found boring in quite some time. Most Stormcast stories revolve around minor Stormhosts or the fan favorites of the Astral Templars, Hallowed Knights (especially Gardus's Chamber) and the Anvils of Heldenhammer.

But a fun thought. The Hammers of Sigmar are not the Stormhost with the most aesthetic similiarities to the Ultramarines. There is another Stormhost of boisterous warriors turned soldiers, with brash braggarts and dour captains, glory seekers and friends to the baseline mortals... the Astral Templars. So while there is a lot of overlap, if you really look at it you might notice that GW did go out of their way to put unique spins on those overlaps.