because litecoin brings nothing significant to the table that bitcoin does not have.
+1What Litecoin brings to the table is that it is a viable alternative. That doesn't count for much (as shown by the disparity in values), but it does count for something.
Litecoin is a couple years behind bitcoin in adoption, and it will be a tough road to mass adoption because it will always be overshadowed by bitcoin. I don't know if it will succeed or not, but I think it will.
If you buy an AMD chip you can still use the same programs as people who use an Intel chip.
If you buy litecoins you have a different currency, incompatible with bitcoin.
I am free to buy an AMD chip because this will not prevent me from doing stuff I would do with an Intel chip, since they are compatible. They are compatible alternatives. If I need an Intel chip, I can buy an AMD chip instea and be fine.
If I need bitcoins, I buy bitcoins. If I need bitcoins, buying litecoins won't help me, since they are incompatible with bitcoins.
Get it now?