We can do it that way. You just end up with many of the same issues we see today being exacerbated further, like rule of law not being followed and a lack of understanding about the legal structure.
The point of citizenship distinction is part of organizing a democratic government and maintaining cohesion. It tests a person on the basic form and laws of the government and their allegiance to the tribe. The point here is that you have a group off like-minded people allowing other like-minded people into the group. This creates a cohesive group that agrees on basic principles and can function well. Think about trying to conduct a system architecture design meeting with the non-technical users weighing in through a democratic vote on each suggestion - are you excited to do your job in that scenario? Do you end up with lemmings following the best salesman without understanding what is going on? (Different opinions are fine as long as they are legitimate and don't violate the common principles)
Letting anyone in makes the knowledgeable people feel disenfranchised by mob rule, not to mention making the organization susceptible to subversion. There's anecdotal evidence (probably statistical evidence if we look around) to support that citizenship that is earned results in a population that is more involved (look at voter turnout in places that never before had free elections).
So while I agree that people in a given location should have say over their government, I also believe that in being a part of that democratic government they have the responsibility to learn the basics by which the government functions. This minimum requirement at least shows a good faith effort on the part of the individual to be a diligent member of society.