Someone proposed in the past that the value of a cryptocurrency tends to follow the amount of hardware devoted to processing said currency...
The value of the hardware plus the energy to run it. If a coin doesn't at least break even, then people wont mine it unless they just want to burn up money.
I think FTC is undervalued atm. the recent hash rate increase has caused the ROI to halve so unless the price of the coins goes up soon people will start mining something else. I think FTC should be worth about a quarter of LTC, it's currently well below that. Scrypt mining is a lot more expensive than SHA256 and that has to be taken into consideration in the coin price.
FTC is currently 250% more profitable then BTC .. so people will continue to mine it until gets to ~110% (basically next difficulty update)
Everyone believes LTC should be 1/4 of bitcoin but it hasn't gotten there yet.. give it a year or 2 and should be more realistic pricing... but about another 10000 alt coins out as well which is making the market polluted