This point is kind of weak... i mean you can buy a fraction of bitcoin and here you go.
Exactly, they fill no niche market. Maybe Dogecoin did since it was used as a tipping currency, but Litecoin is simply a Bitcoin clone aka the first shitcoin.
The Litecoin is "silver" to Bitcoin as "gold" has always been a silly argument to me, since Bitcoin can be as little as one satoshi (0.00000001 BTC => currently worth US$0.00000477). It is hard to imagine a scenario where you actively need values less than that, although at times transaction fees on Bitcoin can be an issue on small amounts. Service-level wallets are an easy solution to that point though.