Maybe you should replace the word "Ethereum" with "sotware". "Software in general makes sense is all the following are true"
Software in general doesn't exist in a vacuum - it's backed by all the centuries-old meatspace institutions like common law, courts, and lawyers that provide a recourse when something goes wrong. As I understand Ethereum's whole purpose is to replace a lot of these institutions with "smart contracts" (correct me if I'm wrong). If Ethereum has to rely on the same institutions as every other piece of software to deal with contract disputes isn't it just adding more complexity to transactions?
Now, I'm skeptical of Ethereum's suitability in this space - the design doesn't seem to be geared enough towards correctness. However, they've also done some things that I really like (e.g. rolling back The DAO), so I'm not counting them out just yet.
To clarify, my point isn't "software has bugs! don't trust it for anything". My point is "software has bugs! don't make it the forum of last resort for contractual disputes".