Actually, no. There's no need or possibility to make it "cleaner", but there's always the direction of making it more "high level". These are very different things.
The platform APIs are not opinionated about templating, they just provide proper mechanisms for declaring elements and having isolated DOM subtrees. It makes sense to leave templating to libraries, because… well, good luck on getting even just two people to agree about how templating should be done :)
If you look at https://lit-element.polymer-project.org — it's just a base class that integrates declarative DOM templates.
The platform APIs are not opinionated about templating, they just provide proper mechanisms for declaring elements and having isolated DOM subtrees. It makes sense to leave templating to libraries, because… well, good luck on getting even just two people to agree about how templating should be done :)