As I read on the latest edition of The Economist an excellent report on how the major Gulf carriers (Emirates, Etihad and Qatar Airways) are changing the global aviation market ("Rulers of the new Silk Road"), Qatar Airways is starting its new Doha-Barcelona direct flight (as I already mentioned a few months ago).
If the emergence of the Gulf "super-connecting" airlines (I am borrowing some terms from The Economist here) has had a profound effect on the World's air traffic, the new Qatar Airways Doha-Barcelona, although of small quantitative significance with regard to Barcelona's volume of passengers, is also a very important qualitative change for the Catalan airport.
If there is one thing that BCN lacks, it is long-haul routes, which are almost non-existent in an Eastward direction. This deficiency is, partly, compensated with the frequent connections that Barcelona has with main European hubs. As BCN has traditionally lacked a flag carrier of its own, the likes of Air France, KLM, Lufthansa have viewed BCN and its influence area as a large feeder market (the absence of flag carrier factor might be key in explaining why BCN's number of long-haul connection is much smaller than that in airports of similar size with catchment areas of a similar level of economic and demographic development). This was ok (if obviously not ideal) if you wished to travel to major cities in other continents: Beijing, Shanghai, Tokyo, Bangkok...they are all just one stopover away from BCN.
However, and as The Economist also notes, one of the strengths of the Gulf carriers is that they have diversified their networks to cover multiple secondary markets in the Middle East-Africa-South Asia region. The importance of the Qatar Airways connection can then be understood in this way: it not only adds a new destination in a previously undercovered region (the Persian Gulf), and an additional East-West connection route for Barcelona, but it also puts a large number of secondary markets within one stopover of BCN. Getting from BCN to places like Melbourne (Australia), Kochi (India), Dammam (Saudi Arabia), Dhaka (Bangladesh), Kathmandu (Nepal)...or even the Maldives, could involve complicated and costly route plans with multiple transfers.
The significance of this new route for the Barcelona market is not only that it gains access to a prestige airline renowned for its excellent service, but that the size of the globe has shrinked overnight in an Eastward direction.