Ethereum is a currency and enforcement system built for computers. Initially, ambiguity isn't a feature because it's meant for contracts and things which are meant to be precise. Room for ambiguity in ethereum can be added later, once computers are intelligent enough to negotiate ambiguity.
The main feature of this system is removing the need for enforcement. Think about how much goes into maintaining police, bounty hunters, debt collection services, reposession services, prisons. In many people's opinions, if enforcing a contract is possible through software rather than physical force, software is always preferable. It brings its own issues of course and isn't instantly perfect, but the possibility of a world with much less need for violence to enforce the law is worth pursuing.
The biggest advantage of this is that it can be completely automated. Corporations can be programmed to run themselves and negotiate enforcable contracts with each other without any human intervention. You could have a personal digital assistant which interacts with other digital assistants to manage your finances and investments, and everything can be enforced by software. As long as enough people are running free software, everyone can share mutually beneficial enhancements to the algorithms which govern their behavior.
You might not want this kind of thing today instead of a trained financial advisor, but 30 years from now, it's likely that software will be better able to make financial decisions than any unaugmented human. Even more important would be movement of commodities around the world between people who need them. Instead of relying on profit-motivated markets to distribute goods, we could have optimal algorithms for moving resources where they're most needed, and enforcement of these agreements will not depend on the strength of a nation's military or economic power but rather smart contracts which are perfectly enforcable whether they belong to a first or third-world nation.
None of this comes free, and there are real challenges to overcome. People will try to exploit them for personal profit. Software will have bugs and make bad decisions. Those are some of the growing pains we'll need to work through to get to a more fair, less violent world.