I personally have an root level override to do this, but it'd be fantastic if this was in the core baked in.

This isn't much to ask for :)

1. Ability to add all available input types (missing: time, number (not telephone), range, color)
2. Add "required" (on required inputs) to end of input field for HTML5 validation
3. Add common "patterns" in a dropdown for HTML5 validation on text and telephone inputs. Such patterns could be "no numbers" for text inputs being used for a Name question. or "no letters" for telephone inputs.
4. Basic server side validation on the telephone field.