I thought the change in the "no feedback left about buyers" was because there were too many sellers who would retaliate if their buyer had the audacity to question them or if the buyer left negative feedback (even if it was deserved).
And since buyers usually do FAR less volume, the buyers were feeling that their own ratings were more at risk, and it would hurt their chances to buy. And they just in general felt less safe.
And it meant that buyers were less likely to leave deserved negative feedback, so the entire ratings system lost some credibility.
It's probably still not perfect, but that's why I thought it was changed
I personally think Ebay should go to a three-star system instead of a 5-star.
3 stars = no problems (minor delays OK), safe to order from
2 stars = some problems, all resolved eventually, but safe to order from
1 star = lots of problems, or problems resolved but not that satisfactorily, might be OK to order from, maybe
0 stars = not safe to order from