Sure, but is the smell because of OData or is that smell mostly coming from the messy old enterprise cruft that an OData veneer has been applied over? I can't really speak to how Dynamics did this in detail, but on my crusty enterprise platform with a huge existing api surface we did a veneering project as a rest v1 using OData (intentionally avoiding esoteric bits, but using query, $metadata, and limited relationships). It does have an enterprisy cobweb feel in places but I think that'd be present if we'd done it without OData as well.

For that matter, I know it's "bad" to use RPC, but imho it's sometimes the cleanest/simplest interface you can make for something on an API.

You should never have to apologize for delivering value - that's ultimately the purpose of technology. If it's the cleanest/simplest solution to a given requirement, implement it and move on - don't worry about trying to appease cargo cults. Technology should be used as a tool to deliver the best value you can within a given set of requirements. End users don't care how many Internet points from fashionable tech du jour you collect along the way, all that matters to them is the end user experience, invest your energy towards that.

There's nothing wrong with RPC APIs. Other than being "Not Cool" due to the legacy of SOAP, they can deliver some very nice value.

Various RPC mechanisms like Bond and Protocol Buffers (and more recently GRPC) are trying hard to make RPC cool again. Personally, I hope they succeed, as REST (like any technology) doesn't work for everything.

For that matter, communication abstractions over websockets... Which has been most interesting to me in terms of offering some better security choices.