This I really don't understand...because I really like superheroes and I'd probably enjoy watching them seep into everything like poison gas, but I haven't. ^^;
-I don't think character designs 'looking like superhero costumes' automatically means the designer was trying to copy superheroes. What is a superhero costume anyway?? If you're talking about the traditional "underwear and tights", then that's actually kind of going away across the board (even Superman doesn't wear that anymore, in recent designs); I don't see why that would be spreading. And if you're just talking about leotards, then...that's...not a superhero costume. It's a leotard. People wear them for functional reasons; they existed before the MCU...
-Superheroes don't 'steal from other genres' if they change the style of their costumes...if Luke Cage wants to go around in a gray hoodie instead of a flashy suit and headband nowadays, that's his right. It...literally IS more realistic, because the average man would more easily be able to obtain the former than the latter. Besides, who is he stealing from?? Who suffers just because a superhero isn't wearing red and blue with lightning bolts?? I really don't get that complaint.
-And if you really think a "superhero costume" is the stupidest thing in the entire genre, shouldn't you be pleased that some modern heroes are declining to wear them??
This is the exact reason I love the superhero genre. It's basically the last refuge of 'camp' in our entertainment landscape: That special, silly place where you do fun things not because they're practical or realistic, but because they're the fun things to do. You design the silly costume, you make up the silly nickname, you deliver the snappy one-liners and rescue the cat from the tree. Not because you need to, but because it's fun and now that you're a superhero, it's your turn. ^^
You shouldn't expect pure realism or even complete seriousness from the superhero genre. It defies logic simply by existing...and if suspending your disbelief that far is too uncomfortable for you, I don't think it means either of you are doing something wrong. It just means it's not the genre for you. =/
-I don't think anyone actually expects every sci-fi character to come with powers, sidekicks, and an arch nemesis. You're free to create one at any time that doesn't have any of those things...and if you end up getting backlash for it, please let me know, because I'd be VERY surprised to hear it.
-None of those things are exclusive to superhero stories anyway...a good arch-nemesis is a staple of romance dramas. Sidekicks are common in "Indiana Jones"-type adventure stories. And special powers are everywhere...this really looks like a case of either "seeing what you want to see" or "because one prominent creator is injecting superhero tropes into sci-fi, they must ALL be doing it now"...
In conclusion, you don't have to like superhero stories. But it feels really unnecessarily hostile to go from there and declare everything associated with them to be 'unclean', and then also demand that the genre stay the same forever and never evolve, because change would equal "stealing".
Like, if you don't even want to read them, I don't think what authors do with them is any of your business...in any case, just because they're popular now doesn't mean they're everywhere.
People love to make that complaint, even though the reality is that plenty of content creators AREN'T following the current trends, and their work will still be available for you to look at when you're finished trying to tell other people why what they enjoy is wrong.