3D as a means to turn growth in the sale of televisions is an extremely failed concept. People just don't want the glasses, and really don't want 3D at all. Not ALL people, but 'people' as a collective general prejudiced statement. People don't want the hassle, people don't like how it looks, people don't want to have to pay more for it, people don't get it.
Moreover, the technology is confusing and doesn't always work correctly. Painfully complex at times, and certainly a desert of non-information out there. Try to research different format types, and what any TV is actually capable of. Talk to all the people who download 3D content, then compare that to those who are watching on Blu-ray. Try, for a bit, to figure out passive 3D content... Then try to ask a sales associate for help.
4K is easy. It generates sales, and if properly implemented, at the right size, from the right viewing distance, actually can improve the viewing experience.
Still, at the end of all of this, viewing 3D on my 161" screen, with good 3D glasses, is a heck of an experience which easily surpasses the 3D experience which I get in movie theaters and has actually made me more excited about using the technology. It will get me buying a few more discs which I would not have considered, and with the significant price drop in glasses, it's no problem having a few extra pairs around for friends as needed.
Failed? Yeah, in most regards I agree completely. But, anyone who enjoys 3D in a theater and wants to recreate it at home does have that potential and option, and is truly capable of exceeding that experience, which is the one part of the tech that is not a failure, but seriously cool.