Defaqto and other ratings agencies have been attacked for "driving the wrong behaviour" by encouraging product complexity and being "in danger of misleading consumers".
However Defaqto has explained its ratings are produced in consultation with providers and were weighted according to their importance.
Speaking at the Bright Grey and Scottish Provident Future of critical illness (CI) conference, Roger Edwards, proposition director of the providers, said despite falling sales, insurers had been adding conditions covered.
"I've often thought this practice was not right and might make it more confusing for customers," he said.
"Unfortunately the way the industry works is if you don't have a long list of illnesses you tend to fall off the Defaqto score and panels.
"Therefore the market pressure is to add illnesses to gain competitive advantage - we did that in May and our sales have increased," he added.
Edwards was backed up by Nick Kirwan, assistant director of health and protection at the ABI, who said: "My worry is some of the systems are driving the wrong behaviour.
"You have independent commentators scoring products and allocating extra points for being struck by a meteorite, so we all have to do that.
"And arguably - although we have seen some improvement in this - the points allocated have to be proportional to the cover, because if they are not I fear we're in danger of misleading consumers," he added.
Ben Heffer, insight analyst at Defaqto, was not at the conference so did not respond directly to the criticisms, but clarified that a range of factors are used.
"Two or three years ago we moved away from scoring on the number of conditions to the value of cover," he said.
"Marketers wanting an edge over their competitors have appealed to IFAs with relatively simple messages like ‘this policy has x number of conditions and this one doesn't'.
"As part of the rating process we have our forum and invite the providers along to discuss the criteria and get feedback," he added.
