If I could create my own blockchain network I think I'd follow the trend and create something that's meant to be a blockchain version of an already existing app or service.
I think I'd create blockchain that would be specifically designed for voting. I don't know if something like that exists but if it doesn't then I'd be the first person to make it. The blockchain would be set up in such a way that people would be able to do things like simple class rep elections or nationwide elections and since everything would be recorded on the blockchain, there'd be no chance of rigging.
I'd create it specifically for Nigeria because free and fair elections don't exist over here. The blockchain would of course be usable by any one, be it government or high school student. Considering the fact that in the last US elections, I saw on the news that some Russians apparently hacked the voting register and helped Donald Trump win(Not entirely sure how true this was) but then again it shows how unreliable present day voting systems can be.
Every person would be required to register themselves along with their passports and social security numbers or in nigeria it would be your national identification number. Votes will be casted from the comfort of your own home, simply by going online, providing the relevant information and clicking on who you want to vote for.
I'd also try to throw in a feature for extra security where the fingerprint scanners from people's phones or the face/retina scanners as well would double as a means of verification before the vote will be cast.
Since everybody's details will be recorded on the blockchain, there won't be anything like excess votes and seeing as people's biometric and personal data would be saved on the blockchain, it would be impossible to cast a vote using someone else's account.
For the sake of those who don't have smartphones, voting centers would be set up with biometric scanners for fingerprints, eyes and faces so that no matter what, if you don't pass the verification, your vote will not be registered.
As far as how important it will be to the world, I think it would be the perfect way to completely eradicate rigged elections and be a bold step in the right direction for democracy.