how to make Bruisers more fun to watch/play as:

really good regen items. What's more frustrating than a frontline that can't stick around because they got hit by a nidalee spear? What's more annoying than the fact that your Maokai has to recall instead of contest Dragon because he's OOM? Nothing, that's what. A champion can't make "the BIG PLAY$" if they can't stick around to contest things. The main difference between carries and frontlines should be that frontlines are tankier and have more sustain. Right now there's hardly any difference.

is a great start; is fine as well. But there should still be a few more good items that grant regen than these.

Another item that can be built from is a no-brainer. could use another item to be built into as well; why not have the two of them share a build path? Maybe it could have 's unique passive but on-hit instead of upon being hit.
Why isn't granting more health regen than it does I have no idea. Maybe and could have 150% and 200% regen respectively instead of 100%? That might make them more attractive; people might start thinking of it as THE siege item then instead of just another