In particular, ethics allows signalling virtue. Ethical systems are typically fairly other-oriented and they are frequently involved in manipulating the behavior of others. A shared ethical system can be a badge of group membership. A concern with ethics signals affluence: poor folk are more interested in means to obtain food and shelter.
These benefits are part of why humans are interested in ethics. However, from the perspective of memetics, these benefits aren't the real function of ethical systems - since they accrue to the human hosts involved. Since ethical systems are socially transmitted memeplexes it is reasonable to ask how their features benefit not their hosts, but themselves.
In memetics, the primary function of ethical systems is to spread. To do this, they need to be extensively publicly discussed. They also need to be taught to other individuals - the younger the better. This perspective probably helps to explain why there is so much public discussion about ethics. Not only do humans signal their virtuous nature to others by exhibiting their ethical systems, the ethical systems are themselves directly adapted to spread between hosts via teaching and instruction.
The signalling aspects of ethics play double-duty. On one hand, ethical signalling ethical content lets human hosts signal to other humans how virtuous they are - and how much spare time they have. The signalling of ethical content also directly helps ethical systems to spread.