This is true. But even after Silk Road the use of bitcoin in the Dark Web is enormous. According to CoinDesk "Dark Web Markets Processed More Bitcoin than BitPay in 2014". Following some data from this article:
"... Kyle Soska and Nicolas Christin from Carnegie Mellon University revealed that even by conservative estimates the daily sales volume of six large-scale dark markets reached up to $650,000 in 2014.
The bitcoin merchant processor's self-reported annual total, $158.8m, would produce a daily average of around $435,000."
More can be found here: http://www.coindesk.com/dark-web-markets-processed-more-bitcoin-than-bitpay-in-2014/
So the people have right in thinking that bitcoin is used mainly from the criminals and culprits. The only thing that can fight this is the regulations of bitcoin. In this way, bitcoin will be known by to many other kind of people, will be owned and used by them and will be not more only an illegal currency used by the above firsts people.
As for being more than a financial tool to obtain drugs this is more hard to be understand and explained because even to many of us which have time in learning and using it is hard to find which of its technological qualities can (might) be used or have importance in the real life except being an currency.