Because it is currently selling for around $25 per coin and is in a position to expand rapidly this year. A jump from $25 to $50 would be the same as BTC going to $2,000.
Look at Coinbase; they just signed Overstock.com and are currently viewed as the largest American exchange service. They will likely continue this growth as more large mainstream companies get into BTC. These companies will align themselves with only the most reputable exchange service.
The inventor of Litecoin is working at Coinbase and it's a safe bet to assume that Litecoin will find a place on Coinbase sometime in the future. Litecoin isn't going anywhere people. You can mine it reasonably with your GPU. The grassroots of Bitcoin is supporting Litecoin and it's expanding rapidly.
Think about the impact of being able to spend Litecoin at Overstock, Netflix, Amazon and any other mainstream company that realizes the immense business opportunity with accepting Bitcoin and aligns themselves with Coinbase or another exchange service who later adds Litecoin support.
If you own a company who accepts Bitcoin to instantly sell for USD then you would accept Litecoin without thinking twice about it. Especially when your "merchant service" allows it with a lower rate than conventional payment processing. I can't see it going any other way. Litecoin is about to hit the sky.
If anything I consider Litecoin a more attractive opportunity than Bitcoin right now because of the price point. Going from $25 to $50 each will double your buying power and I can easily see $300 to $500 or more before the end of this year.
To put it in perspective: if LTC were to go on direct exchange for USD and the market volume brought the price to $400 that would be the equivalent of BTC going to $16,000.