I don't even know if viewers would have paid that much attention to what was going on in Metropolis, except that the whole mood of the movie was so depressing and joyless to begin with that it highlighted the fact that the destruction was causing real pain, and Superman was either unable or unwilling to assist at some level (either explanation would fit in given the mood of the film). That same gut response wasn't felt in Avengers, where the heroes and situations did seem genuinely fun and hopeful on some level, as most comic book characters were meant to be. Here you've got sad sack Pa Kent giving bizarre speeches and committing suicide, you've got brutal, self-hating enemies, you've got a grim, desaturated Superman essentially threatening the U.S. government and killing his enemies, you've got destruction and death on a massive scale, it all feeds into an overall mood that highlights the suffering and pain that really shouldn't have been the focal point of the first Superman reboot movie IMO.
