To be fair Sennheiser make some genuinely decent kit, it isn't bling and flash for the sake of it. Look at their product range and the kind of accessories you cite are conspicuous by their absence, they're not the same as e.g. Beats, charging a premium for stuff that is at best mid-range.
Yes, a lot of the premium priced brands are simply marketing with nothing of substance to back it up, but genuine high-end audio gear commands a fair price too. You need to distinguish between the two.