We can not ignore that the development of electric with high power brushless and high capacity LiPo's did make electric racing/bashing more exciting. Also with RC flying has almost taken over the gas powered models.
But beside that on many forums where many bashers and beginners hang around the word is told that nitro is difficult with lots of maintenance and tuning so beginners will search for electric.
And from the shop vision you can not blame them, there is more demand for electric. But they are also a bit tired of customers coming every week to re-tune their engine(s) because they can not do it by them self.