Renaming MCs is a definite for me (unless the MC default is already the name i want lol) but when it comes to naming LIs/others i usually just stick with the default as it can be confusing when talking to others about the game and not having a clue who they mean coz they renamed a character.
I always rename MC to my own name, and if I get the option, I use an anglicized version of my last name. I appreciate the option to rename primary LIs, but I usually stick with the defaults. Making it a requirement to name both myself and my primary LI makes things difficult - for instance, and I apologize for naming/referring to another VN/game here, the one single gripe I had about DMD, was that I was required to name the primary LI, without any defaults to fall back on (those who've played this one, know what I mean). In that case, I decided to pick the name of another LI from another game.
But back on topic, I agree that all VN/games should have the option to rename the MC, preferrably both first and last names (if a last name is ever used in the story), and if either is left blank, the developer should have default names ready.