It's fine if we get more merchants.
However, it's not fine, if they just follow the money, and they convert all their bitcoin received, back to fiat.
This will just #$$^^ the price, due to over supply of bitcoins, back into the market. ^Frown^
We all know, that the more Bitcoins that are for sale, will decrease the value. ^Sad^
While spending bitcoin will create the same effect as selling bitcoin on the price, it is what bitcoin is designed for as a payment system. It is IMO not a good idea if everyone is hodling their bitcoin, as bitcoin will become useless.