No i dont think its is the exchange rate. as you can see the exchange rate is very good.
I think that lack of knowledge of bitcoins to the world and bitcoin not everywhere acceptable can be the two reason.
but things are improving in the favor of bitcoins.
I think its still rare in the world stores or merchants that accept bitcoin as a payment option. but its will not make people stop to using bitcoin. will be very easy to solve this, you can immediately convert it to fiat. very easy.
I agree with the exchange rate is very influential