pros only make up around 15% of the market. Consumers make up the rest.
True, but pros have high marque value, they have a disproportionate impact on the direction a company like Canon goes and their community's take on things tends to filter down through the rest of the consumer base.
Marketing and engineering love to focus on the 'power users' of their industry, reviewers like to focus on them, and consumers like to feel that they are not going the 'toy' route which means looking at what the 'real' users are avoiding.
Photography is a VERY image conscious hobby, with large numbers of 'average' users trying to look as professional as possible, and significant numbers of professions trying to differentiate themselves from 'guys with cameras' or 'prosumers'.