Here's an interview from 2017 with Evan where he discusses Elm's approach to interop. https://elmtown.simplecast.fm/b06499a6 Skip to about 8.5 minutes in.
While Luke's approach certainly could have been better, I don't think it had any bearing on the result. The reason for not allowing Javascript into Elm libraries seems fundamental to what Elm is trying to achieve.
https://elmtown.simplecast.com/episodes/it-just-goes-on-and-...
Obviously Microsoft is a huge company so they use all of the languages, but I find it surprising given the amount of investment they've made into Typescript.