https://www.etymonline.com/word/eso-

eso- word-forming element meaning" within," from Greek eso “within” (see esoteric).

https://www.etymonline.com/word/exo-

exo- word-forming element in words of Greek origin meaning “outer, outside, outer part,” used from mid-19c. in scientific words (such as exoskeleton), from Greek exō (adv.) “outside,” related to ex (prep.) “out of” (see ex-).

Because people think it’s exoteric rather than esoteric. And one thing people hate is walking through the hell inside to get to heaven.