Yeah, I agree and I'd actually like to recant a bit on my first post. The lyrics might be clumsy inasmuch as they refer to 'Africa' rather than specifically the Eritrean province of Ethiopia (where the famine mainly was centered), but pedantically sneering at lines such as "Where nothing ever grows / Nor rain nor rivers flow" by saying that the writer was obviously unaware of geographical facts such as the source of the Nile, or agricultural facts like they grow yams in Ghana, or the details of the two rainy seasons in the Serengeti is a cheap shot IMO. It can, and should, be excused under the banner of 'poetic licence'; the song wasn't meant as a geography lesson. (And yes, they did know it was Christmas).The lyrics rather clumsily try to compare what was happening in Ethiopia with our comfortable Christmas. For me 'do they know it's Christmas time?' is more about pointing out that they have other things on their mind.
I always assumed the whole point of the Christmas references was to guilt people into buying or donating at a time of year they are celebrating. The' won't be snow in Africa this christmas' is written to highlight the difference between us and the people they are raising money for. This is more clumsily/directly stated in the much maligned line' thank God it's them instead of you'.
I know there is a lot said about the lyrics not having aged well but I think that in these contexts they make more sense and they certainly served their purpose at the time.
And, as I said before, at least they did something which is more than a lot of people have done, either before or since.