In particular, mining brought a huge number of people into Bitcoin that weren't there before. Stories about how people had made tons of money getting into bitcoin early and mining bitcoin with their gaming computers brought a pretty large contingent into the fold.
A lot of those hobbyist miners put money into additional GPUs and ASICs, and then got burned by companies like Butterfly Labs and MtGox. This let to a lot of people slowly leaving bitcoin and many of those that remained have become a bit cynical.
That's not to say that Bitcoin can't or won't recover, but I do think it has a bit of a user adoption problem. There are a number of tech and financial companies that are looking to leverage the technology behind bitcoin to solve problems like remittance and in the process build new institutions. However, most of these companies make money off of transaction fees or trading fees. These companies won't rely on the price of Bitcoin going up hugely per se, but rather on the idea that people will make transactions over the network.
Put simply, the price of bitcoin has been going down because less people are coming into bitcoin. In fact, I think there is probably some net attrition going on.
This may change, their may be some other factor that causes bitcoin to jump up and more users to join, but for the moment there appears to be a net attrition corresponding to a decline in price.
That is true, I adopted bitcoin early 2013-2014, so at that point, mining was dead to newcomers.