With the recent changes to heavy armor cost and addition of some powerful weapons (stormbreaker, jebbal claws and acid arrows) heavy armor is actually worse now.
You wanted to buff it but in context with the other additions there is no buff in practice.
However if heavy armor would confer an immunity to bleed it would become a real option. Its usefulness would still be situational. Not being able to dodge roll means you have to be really lucky with hits and finish the fight quickly. Otherwise the opponent can stack poison and bleed on you, because he can hit you easily, which will kill you. Damage reduction means nothing if you have constant damage and can’t heal.