have you actually read the given links? Detailed explaination is given in the links provided. Of course there's a difference in status between a wife and a slave. However, Islam already sets the minimum rights that belongs to the slaves. Of course the best option is to set the slaves free.
Also regarding a wife as a "possession" and how is it different from "property", it's better to read the tafseer and 'alim's commentaries on that that will clarify it.
Allah Knows Best.