I have no misunderstanding for heroes' roles in edain 4.0, that's exactly why I have this concern. Heroes can be killed by massive hordes easily, they are more like support in battle, I have no problem with that, actually I agree with this change. The problem is, in this case do we really need a hero killer role in the game? If I spend those resources in units, I could have a huge advantage in hordes against my opponent who puts more than 2000 resources only for one hero. Hero killers are more like assassins now, they are brittle and of little use in fierce battle in front line. Eowyn is the most typical and practical hero killer so far, because she is cheaper than most of the core hero(with leadership) of other faction, that's the idea, hero killer should be cheaper than their goals. Lutrz, as you said, is not that a pure hero killer,although the team claimed him to be, since he does have powerful leadership for late game.
To the contrary, Aragorn's role in Gondor is rather awkward. He is too expensive, in regular game one cann't recruit him in early game, while in the middle game when there are already massive units on the battlefield, he is already of little use. Even with his ability, there is no guarantee he could kill enemy core heroes(with higher levels) and remain alive after that, not mentioning his opponents are usually cheaper than he is. He has no leadership(I don't even want to talk about his final leadership), you claim he has support aspect, care to specify? If you mean "Athelas", I have to say this ability is negligible in middle game, its effect can hardly recover 1/4 of hero's health. His final ability, I won't speak for others, but I never find that powerful, it looks absurd, the undeads just stand here, sometime not even attack, do you really expect you enemy see the undeads stand here, and still go there to get themselves killed? At least they should make these undeads move with Aragorn. In my opinion, Aragorn for this version is worth 2000 at most, even so I will hardly recruit him before trash time in one game. And the hope of men, the first king of reunited kingdom deserves more than just that.