on the surface, secret identities are pretty silly. but so are superheroes in general. having said that, I miss the use of secret IDs these days. it's part of the fun of superheroes, the idea of "putting one over" on family and friends in the guise of "keeping them safe".
take Spider-man here. no way would anyone be able to take this guy seriously in this costume, nor would the costume itself ever be feasible in real life. of course, no one would take Peter Parker seriously if they saw him climbing around walls, they'd lock him up for either his safety or secret military experiments to find out how he did it.
but the readers of Spidey comics didn't care. and Lee and Ditko knew that. just present the character, tell the readers "in this world, this is how things work" and let it go from there. don't try to explain why he can stick to any surface, since we know spiders can do that (and how many people actually know why? exactly.).
comic books used to be intended for kids probably aged 6-12 years. I'd say DC upped it a bit in the 50s with their use of the "new" heroes and the added science, and then Marvel made it OK for college kids to read comics in the 60s.
Stan Lee said in "Origins of Marvel Comics" that he disliked secret IDs, and didn't use them for the first hit, The Fantastic Four, to great effect. however, nearly every hero after that had one.
I'm not exactly sure what all this is for, just that I like secret IDs. sure, your superhero pals would know who you were secretly, that would almost be a relief to have some peers to confide in. but established superheroes without masks and costumes and all the trappings of comic books?
meh, I'm just not that interested in them.