I disagree on several points here:

1. I think attributes absolutely should exist. They're great for describing metadata related to the tag: e.g. element ID, language, datatype, source annotation, namespacing. They add little in complexity.

2. The point of a close tag with a name is to make it unambiguous what it's trying to close off.

It sounds to me like what you want is not a better XML, but just s-exprs. Which is fine, but not quite solving the same problem.

3. As far as schema support, it seems to me that JSON Schema is well-established and perfectly cromulent – so much so that YAML authors are trying to use it to validate their stuff (the poor bastards) – and XML schema validation, while robust, is a complex and fragmented landscape around DTD, XSD, RELAX-NG, and Schematron. So although XML might have the edge, it's a more nuanced picture than XML proponents are claiming.

4. As far as tabular data, neither XML nor JSON were built for efficient tabular data representation, so it shouldn't be a surprise that they're clunky at this. Use the right tool for the job.

Attributes exist due to it's origin as a markup language. XML is actually (big surprise) a pretty good markup language. Where the tags are sort of like function calls and the attributes are args. With little to no information to be gleaned out of the text. The big sin was to say "hey the tooling is getting pretty good for for these sgml like markup languages. Lets use it as a structured data interchange format. It's almost the same thing". Now all the data is in the text and the attributes are not just superfluous but actively harmful as there is a weird extra data axis that people will aggressively use.

Hard disagree about attributes, each tag should be a complete object and attributes describe the object.

    <myobject foo="bar"/>
    // means roughly
    new MyObject(foo="bar")

But objects can also be containers and that's what nesting is for. There shouldn't ever be two dimensions in the way you're describing. The pattern of

    <myobject>
      <foo>bar</foo>
    </myobject>

is the root of most XML evil. Now you have to know if myobject is a container or a franken-object with a strict sub-schema in order to parse it. The biggest win of JSON is that .loads/.dump make it really obvious that it's for serializing complete objects where a lot of tooling surrounding XML makes you poke at the document tree.