ObjC interoperability is a solved problem now for Swift. They are even adding C++ and Java interop too!

it is, but it definitely added some weight to the language. At least i think so, i'm not a PL expert.

My recent point of comparison is rust, which feels like a much much smaller language, despite sharing a lot of the philosophy (struct + trait, which is very similar to what swift recommends to use nowadays, and limit the use of class).