Perfectly fair advertising as far as I can see........BA have announced they are "launching low fares" to compete with the likes of eJ. It's only natural that eJ and others should respond by challenging that marketing.
You will always be able to hunt around and find examples where BA (and others) are cheaper than the 'low-cost' carriers. We all know that eJ etc. yield-control differently and to get the really good deals you need to be flexible and/or book in advance. However, it is also true that the number of 'cheap' tickets on BA flights is also limited, and I doubt you'd get a good number of 'cheap' fares on their peak services!
The public should by now be savvy enough to shop around a bit. If eJ have persuaded the public by slick marketing that they are ALWAYS the cheapest, and therefore people don't bother comparing the BA prices, well hat's off to the marketing guys and gals for doing a good job!