That view comes following the publication of F1's global media report for 2013, which measures the number of people who have watched more than 15 non-consecutive minutes of the sport during the season.
Twelve months ago, Formula One Management did not publish a total figure, although it was estimated to still be half-a-billion, a drop of around 15 million from the confirmed 2011 figure of 515 million.
This year, however, FOM has not shied away from revealing a sharp 10 per cent drop in its audience, although "not an unexpected one" according to Ecclestone, the organisation's chief executive.
The 83-year-old added: "The less-than-competitive nature of the final few rounds, culminating in the championship being decided ahead of the races in the USA and Brazil, events which often bring substantial audiences, had a predictable impact on reach."
Vettel and Red Bull clinched their fourth consecutive titles with three grands prix to spare as the 26-year-old German and the Milton Keynes-based team won the final nine races of the campaign.
Ecclestone also noted that "the overall effect (of the audience drop) was exaggerated further still when you consider the calendar was one race shorter in 2013".
Overall, though, Ecclestone claims F1 "sits at the very top of annual global sports audiences" as it reaches 185 territories via its 111 broadcast partners who provide between them 27,000 hours of coverage.
But there were substantial drops in countries such as China and Brazil, losing almost 30 million and just over nine million viewers respectively.
The former was predominantly due to a switch from state broadcaster CCTV to a collective of 13 regional partners in order to ensure every race and qualifying session was shown live.
Even in Vettel's homeland there was a drop of around 10 per cent in season-long reach, with the overall figure for 2013 coming in at 31.3 million.
In the United Kingdom, audience figures rose by two per cent between the two broadcasters - Sky Sports F1 and the BBC - to a total of just over 29 million.
According to the report the two organisations offer "what is perhaps the most comprehensive TV coverage available anywhere".
For the coming campaign, with F1 undergoing a technical revolution as turbo technology is reintroduced into the sport in conjunction with the new energy recovery systems, Ecclestone can only hope an engaging title scrap will result in an increase in viewers.
Ecclestone said: "One thing I am sure of is that this coming season will not only offer a heightened level of unpredictability, but renewed excitement and fierce competition."