Isekai as Self-Insert

Finally put my finger on one of the things I really like about Isekai stories: A lot of them are basically overt self-insert fanfic, except both the character you're inserting and the world you're inserting them into are (hypothetically) original.

I never really wrote any Mary-Sues back in the day (despite reading and enjoying a lot of them), but I did write at least one fic where the characters from a fandom I was into were shunted into my world and I had to help them, and daydreamed frequently about what I would do if I visited the worlds of fandoms I was into (with my fandom knowledge intact). From what I've seen, the practice has gone pretty well out of style, but it is something I miss from time to time, and a lot of more standard power-fantasy-ish Isekai stories tend to scratch that itch.

I still kinda miss those fanfics, though. Maybe someday I'll actually do something about that...