The original core, SSLEAY, Was an exemplary instance of somebody outside the core cryptographic community (Eric was, IIRC working as a systems programmer in a psychology department at UQ) -And was hand coded to be both algorithmically faithful to export restrictions (ITAR) and machine code optimisations: it was FAST. The code had to implement both the export restricted brainded reduced keylength and the "illegal to export" algorithms.
Peter Guttmans library was known in some ways to be "cleaner" -But didn't gain traction.
A lot of OpenSSL is history.
Recoding in a type safe language, and with a mind to risks is good. But remember, another attack pattern is differential analysis: Code in crypto has to do some things like present equal cost CPU burden across different paths, to defeat attacks including the side=channel of finding hotspots in the VLSI mask and working out what it does from the leakage of information there.
Its complicated. Rust or Haskell Alone, won't make something like OpenSSL inherently risk-free, it may introduce new risks in closing off these ones.
Still worth discussing. Just not necessarily a no-brainer.