So, essentially, learning Latin will give you a bunch of cognates that may be very useful if you then go on to learn French, Italian, etc.? I can see how this would be useful if you wanted to follow the linguistic evolution of those languages, but if you want to learn to speak them, wouldn't it be more effective to learn those languages directly? Since they have common roots, I imagine that learning one of them would give some advantage when you go to learn the next one.