I think this is super important. In the serverless space, we've seen a couple of larger API vendors (Auth0, Twilio, ...) build their own FaaS. This is great for "Hello World" projects, and projects focused only around that single API.
But I believe that for all bigger projects, that work with multiple APIs, you end up in hell. Some functions running on Auth0 webtasks, some on Twilio Functions and some on a cloud-vendor FaaS? Sounds like a maintenance nightmare.
What we tried is to integrate our events with the three big cloud players. It's doable rather quickly as long as it's just "dumping a message into a queue".
I think a spec like CloudEvents can make such integrations easier in the future, and it would allow us to make use of higher level features of the cloud providers, without having to deep-dive into their specific products. I'm petitioning my PO to give me some time to make our API compliant with CloudEvents :)