I think what it boils down to for me is that Snyder's Superman is too much of a blank slate. I'm not sure if this is a fault of Snyder's direction, Cavill's performances, or the writing (or likely, a combination of all three) but this depiction of Superman rings hollow to me, insofar as he feels like a hollow character. I feel like there were a lot of missed opportunities in the movie -- like the scene where the Dia de los Muertos crowd swarms around him, or when he arrives at the Capitol to give his side of the story (ah but fuck that shit, let's blow up the scene instead!) -- where Snyder, Cavill, et al. could have their Superman actually speak up and stand up for himself, fill in who he is, what he believes in, why he does what he does, etc. All of Clark's motivations and beliefs are told to him -- by Jor-El, by Jonathan, by Martha, by Lois, and, on the antagonist side, by Bruce and Lex -- so this Superman, to me, feels more like a collection of exposition delivered by supporting characters.
The Capitol hearing scene would have been a great opportunity for Clark, in his own words, to really define his character and put forth an ideology that clashes with the grim cyncism of Bruce and Lex and the others. Instead, the scene is cut short by an explosion without, iirc, Clark uttering a single word. It's my main problem with this movie's (and Snyder's) depiction and treatment of Superman in a nutshell.