The biggest problem of bitcoin right now is trust. Actually the lack of it... Lack of trust in the bitcoin system itself, the software and the companies around bitcoin.
The thing is that only time can fix this particular problem...
I would agree regarding the trust as the currency. BTC has to become a currency, not a speculative asset for gambling. This means price stability/growth stability. Then the problem of a lack of adoption will be resolved. Yes, trust is the most important issue.
That's what I've felt for a while is Bitcoin's biggest challenge. It needs to get over the image of an investment and move on to being a unit of trade.