Each state joined the Union as the FULL equal of all the other states. And never agreed to become subsumed to the most densely populated states or to be ruled over by the most populated and highly urbanized areas of the nation and just abolish all state lines. It would mean doing away with an entire level of government -one that is far more responsive to the people than federal government is -because it is CLOSER to the people. Government that is closer to the people is more responsive -which is why anyone with brain would NOT want federal government in charge of any aspect of their life. The majority of states in this country are not densely populated urbanized states and when added together represent the majority of the population -and they don't want Californians for example, who screwed up their own state big time, doing the same to their states. If you are awaiting the day all state lines are abolished and Presidents are directly elected by the people instead of the states, it will be a long wait. The President is the sole elected office who is elected by the states and not directly elected by the people. Because he is President of the United STATES, not the people.
If the people of this country get to the point where they haven't a clue why we have the system of government we do and didn't take the time to learn what has made this nation unique among all others or why we have THE longest lasting continuous form of government in the world even though among the youngest of nations -then do they still deserve to keep it instead of letting it turn into just one more dim copy of an historically proven failure of a system?