I agree with this wholeheartedly. You can even define a standard and let downstream services opt in over time. Simple wins like this should not be put off because "someday" we're going to implement a complex distributed tracing solution.
Often it's political, but political friction can feed into technical friction if there are also a half dozen different half wrappers around half-baked HTTP libraries. Also, if someone has included OpenTracing as a shadow library in a company-wide library (JVM territory), but you want it as a top-level dependency, you have to write translators.
