Well...yeah, it all comes down to personal taste, definetely. I also think getting more distinct animals is a priority, there are still so many animal groups completely omitted in the game.
That being said, we really need to differentiate between what is a genus, a species and a subspecies. The thing with ZT2013 is that, in many cases (lions, jaguars, tigers, rhinos, Asian elephants, giraffe, etc.) those "clone" animals belonged to the same species (aka they were subspecies), with the aggravating circumstance that in some cases the physical differences were almost negligible. In the case of b&w ruffed lemurs, we're talking about a different species within the same genus and with a significantly different coloration than the red ruffed counterparts.
If we broaden the scope to "lemurs", it's important to remark that it is an infraorder where there are about 15 different genera of lemurs. To put this in context: a sifaka lemur is more different to a ruffed lemur than a puma is to a lion. A b&w ruffed lemur is as similar to a red ruffed lemur than a leopard is to a lion or a jaguar.
So, in short, requesting a b&w ruffed lemur makes as much sense as requesting a leopard and more sense than requesting an Asiatic lion (for instance), from a zoological point of view.