It's misrepresentation to suggest that terrorist attacks in London, Paris, Brussels, etc, mean those cities are no safer than touring in TJ, as Pamirski says, in a city of 8 million like London the odds of getting caught in such an attack are vanishingly small. But when there are maybe a few hundred people touring a foreign region like Danghara, targeting a group of 4+ is significant. As a tourist you will stand out like a sore thumb, and we need to accept there is more danger than before - not only is the pressure cooker driving jihadism still there but Islamist fighters have been returning from wars in Syria and Iraq. Not all of those are dangerous, but for sure some will be, well versed in techniques of war and looking for targets to vent their resentment: http://www.atimes.com/prevent-looming-n ... tral-asia/
Should that stop us travelling? In this I agree with Steven's editorial, no, it shouldn't. Not only does this play into the hands of the jihadis who would love to drive a wedge between the ordinary Tajik people and the "west" and deprive them of much needed income, but it would deprive us of the chance to visit this incredible country.
The UK Foreign Office gives good advice on safety and security, worth reading not only for UK citizens, and it's worth noting they don't recommend against travel to the country or to its remote regions, but rather to be cautious and take sensible precautions, something I would certainly echo: https://www.gov.uk/foreign-travel-advice/tajikistan