Types on the left are a parsing disaster. At the very least, a C-style definition demands too much parsing power for questionable benefits. It blurs the boundary between types and expressions and thus complicates essentially everything that has to deal with source codes. This has nothing to do with type inference.

If type expressions were readily recognizable from other expressions (for example, you can force types to be CamelCased and assigned different lexical classes like ML) then it'd be probably a pure personal taste. But a C-style definition? Big no-no.