What problem does this feature solve?

If you've decided to go with v-bind and v-on shorthands then v-on="$listeners" looks out of place and creates a mixture of syntax. Shorthands for v-on and v-bind would solve that issue.

What does the proposed API look like?

v-on="$listeners" should be aliased like this: @="$listeners"

v-bind="$attrs" should be aliased like this: :="$attrs"