I am not exactly sure what else literacy would mean other than the ability to read and write. Those two things pretty much go hand in hand and you can more than likely do one without the other. I have never met someone in my entire life who can not do both if they could do one.
Yes, I approve of the definition of literacy as the ability to read and write, because I'm not sure what else the definition of literacy might entail. If a person is not limited by their ability to comprehend written language, they are literate. That means both reading and writing. If a person can do these things, they are literate.
I definitely think that the definition of literacy as the ability to read and write is accurate. I think that if somebody cannot read or write, then they are not literate. I think that it is something that everybody need to be able to do to be consider a literate.
I think literacy should cover a broad topic and should be primarily determined if someone can read and write at a basic level, I don't think we should be considering comprehension or other similar traits when calculating literacy, I believe it should be kept as basic as possible when determining what percentage of the population is literate.