> any RFC that defines a protocol including binary data will generally go with big-endian numbers

I'm not sure this is true. And if it is true it really shouldn't be. There are effectively no modern big endian CPUs. If designing a new protocol there is, afaict, zero benefit to serializing anything as big endian.

It's unfortunate that TCP headers and networking are big endian. It's a historical artifact.

Converting data to/from BE is a waste. I've designed and implemented a variety of simple communication protocols. They all define the wire format to be LE. Works great, zero issues, zero regrets.