From past year itself Ltc was never comparable to BTC. Just think if you had invested last year 1000$ in both and what return at present LTC would have given you and with that of btc. You would have minted money with the btc and earned some giant profits.
Yes I agree I think LTC and BTC are really different. Although both coins have been in existence for several years, in term of making profit there is no question that bitcoin is really ahead of the competition. And as much as beautiful the project is, people will not look at it, specially investors because they are really in for the profit. And you have a nice analogy, if you invested both starting this year alone, bitcoin will surely gave you a good returns already.