Try telling Texas that it is merely a "province"!
Anyway, North and South Dakota where split simply to add 2 senators at the time. DC is not a state for the opposite reason. Face it, states are completely arbitrary lines on a map.
There is even a poorly drawn line approximately on the 37 degrees north was codified without reference to where the actual 37 degrees north actually was.
Originally DC residents would vote in Virginia or Maryland Congressional elections depending on where the territory was taken from (note: all DC land that came from VA has been returned to VA).
I think the idea originally is few would live in DC; it was tiny for a long, long time. But that's no longer true, hence why we gave DC the right to vote for President. Congress would be trickier given the balance of power, but none of the original motivating factors apply.
(I think DC statehood does sound like a complicated mess, and the best solution -- if politically feasible -- would be to shrink it. You'd have the populous city of Washington, MD, and a tiny federal District of Columbia, coexisting like Rome and the Vatican. The problem is that Maryland doesn't want it.)
You are certainly not from Texas. Stop trying to believe it is leaning center and will someday be democrat/liberal. Texans are the most prideful about their state and are proud of their rich history unlike other top states like California and New York.
That's just one of several very blue parts of a overall Red state. Even with heavy gerrymandering and only 1 close race Texas still sent Dem. 11 vs. Rep. 25 to the House.
And, what remains of state control ends up being a unwanted complexity to a lot of us.
Texans absolutely care about Texas history. You regularly hear the 'we have an independent power grid' and jokes about secession come up in conversation, etc. There are many possible reasons why Mitt Romney would have had a wider margin in Texas than Trump. It's premature to jump to the conclusion that it's turning 'purple or something'.
That being said, Texas is a bigger and more diverse place than popular culture respects. The center of Houston, Dallas, Austin, and similar zip codes are definitely 'blue' country.