The point is, having a choice breeds innovation.
At the protocol level, Litecoin has some significant differences that may ultimately lend it to applications that Bitcoin doesn't. It is insulated from certain issues in the Bitcoin core development, because it is a separate team (although they work closely with the Bitcoin developers) and they have a different design philosophy, in many ways. Bitcoin is going to be under tremendous political pressure from developers and elsewhere to be this or that, whereas Litecoin has less pressure to accommodate. So no...nobody's going to convince me that it isn't a big positive that we have Litecoin around.

That is the one way I could see Litecoin being worthwhile; basically innovating off its differences with bitcoin. The problem is, I haven't seen any real innovation, nor plans for anything in the near future that makes me think litecoin should go up in value.
Of course it may, and perhaps there are things planned that are quite unique. But, again, it does appear to be more a 'stay the course' type of coin, even if that course has been leading downward. I wouldn't tell anyone to invest or not invest in any coin, but I simply don't see a reason for myself to invest in it.