If you think about it carefully, slipcovers, steelbooks, and assorted other superfluous and utterly wasteful packaging trickery are the real gimmicks when it comes to Blu-ray. They typically add nothing of value to the movie experience whatsoever... unless of course you like collecting printed cardboard or metal cases. Yet for some reason, 3D, which actually adds a new dimension (literally) to a movie, and is a valid use of a visual technology that people can choose to enjoy, is frequently dismissed as a "gimmick". You know, if we're going to be logical about this, let's get rid of all the other gimmickry first before wanting to see 3D die off.
People can like what they want. Personally, I'll be happy to see the gimmick end.
That is not a fact. The actual fact is that most TVs now have 3D built-in. For example, in the 2012 Panasonic Viera range, the majority of the sets are 3D capable (UT, ST, GT and VT series). The majority of the 2013 series which has just been announced is similarly 3D-capable.
The fact is that there is not that much demand for it as very few tvs have the option available.