With you so very much. Harry has to tower over everyone. I would not be above achieving this with camera tricksery, Peter Jackson style, but it'd be awesomer if they just found a really, really tall actor who could pull Harry off.
Even if they could afford to do the sort of tricks it took to pull off LotR, it would not leave anything left for all that magic and junk. I would prefer that they find similarly heighted actors in a relative sense, but it's a pretty low priority. Lets face it, the height differences rarely if ever have any impact on plot, we just love it because that and chivalry are the primary source of flirtatious interaction between Murphy and harry and so we dont want to loose it.
By contrast it was far more integral to the characters and their interactions that Wolverine had a Napoleon Complex and Cyclops was a full foot taller than him, aiding their antagonism. But in hindsight I would far rather the actor fit the more central needs of the character, even if the minor details (height, hair/eye color, etc) arent perfect, and I cant imagine anyone doing a better job than Hugh Jackman for Logan.