Realistically if you have a reasonable git workflow any add operation should only have a handful of files that you can quickly scan through to make sure nothing fishy is present and at most interactive mode adds a few seconds to the add process for you to read through everything.
Note: This is an entirely serious question and I am hoping for an answer. I promise I'm not trying to antagonise anyone. I just see so many people reaching for "add ." instead of "add -i".
I say this because I am also a firm believer of if it shouldn't be committed it should be in the .gitignore but I've only ever been burned by that when either myself or others weren't using interactive add.
Basically, isn't it easier to fix a .gitignore at commit time than at PR time?