If there were ownership in bitcoins, when you received bitcoins from another person, you would be exposed to the risk of someone demanding that you return the bitcoins to them, arguing that they are the owner instead of you possible reasons for this could be, for example, if the bitcoins were stolen from them or if the agreement under which they sold the bitcoins was nullified.
http://www.coindesk.com/what-tokyos-mt-gox-ruling-means-for-bitcoin-in-japan/I does not mean a lot, the ruling is political shaped to the current situation. This is the same as any other money. If you are a stealing weasel and you take some money that is not yours then will you have to pay back or enjoy a nice stay in hotel Jail (most likely both). People needs to learn that bitcoin = money. This is also why I always lol at those thread "How do I get 1 BTC fast", same as saying "How do I get $265 fast".