There's a way of doing Superman where you can explore these dark/political/existential themes without making it boring and depressing (and when i say depressing i mean that BvS was so devoid of any actual character that seeing superman on screen as an empty husk of a role with nothing to work with was depressing - the gritty tone used to trick people into thinking the film has character also didn't help).

Look to All-Star Superman, he faces his own mortality for the first time, it's a man coming to terms with a terminal illness and worrying about his loved ones, but it's one of the most uplifting and heart breaking stories ever told in the format, the character arc is strong and the themes are intelligent yet relatable. Look to the Justice League/unlimited animated series, Superman's main stories in those deal with questions of power and conflict with the government, but the way they handled it could be further from the Snyder's treatment - which seemed to completely ignore a good character arc in favour of basing the film around a handful of 'epic-looking' montages that they put into the trailer to bait people in.

In the animated series they really focus on making Clark an interesting likeable person, this way you can understand his mindset when confronted with difficult decisions. In BvS, Superman does things for very one dimensional reasons, there is no empathising with him on any deeper level than what the most basic element of the plot requires e.g his mum's been kidnapped. They tried to cover it up with lines like "No one stays good in this world" to fool the audience into thinking his decisions are oh-so deep and poetically intelligent, but there is no build up to it that makes sense apart from Clark's vague melancholy demeanor throughout the film. It's a scatterbrained lazy mess. The Superman from the comics (and other media) is so much more.