I love your sentiment.Pakistani will be best. For me, it's a useless debate that who should be called what. Are people of Pakistan really working with honesty? Are people getting justice? Do people feel safe?
After all that is achieved, we are ready to be called monkeys. Doesn't really matter what people call us. We will either prove ourselves, or we will vanish. Simple.
What we were referring to was the use of a term for practical purposes. You see Sindhi and Punjabi are ethnic groups, but they are also a term used for practical purposes, census counting for instance, and that affects how different communities are looked after within a country.
By measuring a community within the country, it serves a practical purpose, if they are not being represented, then that needs to be recognized, that can only be done if there is a term, either as a block (Urdu-speaking) or precise term (Pakistan-Behari) etc..
So it has a practical aspect, besides identity as being Pakistanis.