It's a fad, but I think most companies are well aware of this. For them, it's an excuse to sell a proprietary bit of hardware and to differentiate their offeri

It's a fad, but I think most companies are well aware of this. For them, it's an excuse to sell a proprietary bit of hardware and to differentiate their offering from their competitors. It's pretty much what Nintendo have done since the Wii - they couldn't compete on power, so they used gimmicks to differentiate their games from their competitors. They lose out on the mainstream market and numerous third-party games, but they deliver enough quality to sustain a console throughout its lifetime, even if you only buy Nintendo games. Some fads stick around. Nintendo created the rumble pak, and now all controllers rumble. Some don't, like VR and motion sensing. What matters is that they sell.