3D was good for everyone, whether you used the displays in 3D or not - it meant that manufacturers were forced into improving the motion handling of their displays in order to use active shutter glasses.
And 4K is not "fleecing the consumer" either - have you compared Apple devices with and without Retina displays? Same thing.
While not perfect, motion handling, color rendition, and contrast are good enough on my HX900 that I don't care about upgrading to OLED or anything else to improve them now. I will absolutely upgrade as soon as 4K is affordable, and I can get a 4K set with equal or greater performance in those areas. (which likely means waiting for 4K OLED)
SED had plenty of problems to overcome. But considering they were never released, you can keep believing that they were some kind of mythical perfect display if you like.
And 3D isn't all bad. When it is done well, 3D is amazing, and absolutely something I want companies to eventually figure out. The problem is that it's hard to do well.
Active 3D sucks because current displays aren't able to use it without reducing bit-depth and the quality of other processing, crosstalk is a problem on most displays, it dims the display significantly, and it flickers badly.
Passive 3D sucks because it halves your resolution, and 1080p doesn't have that resolution to spare. 4K is a lot better, and 8K would be better still. But you still have crosstalk to deal with, and you need to wear glasses.
Autostereoscopic 3D sucks because it requires you to sit at a specific distance from the TV at a certain angle, and you have a very limited number of angles you can view 3D from. For every position they add, it cuts down the resolution of the display. Even 4K wouldn't be enough to look good, and it affects the quality of the image in 2D mode as well. Crosstalk is still a problem too.
The best 3D presentation I have ever seen is easily the Sony OLED head mounted displays. With one display for each eye, 3D is completely natural and effortless. There's no dimming of the picture, zero crosstalk, no flicker etc. It's everything 3D should have been.
The problem is that the optics were poor, the resolution was too low (720p) and the headset itself was very uncomfortable to wear, even for short periods of time.
The Oculus Rift is another product that goes along this path. The ergonomics seem a lot better, and it fills a much wider view, but you're looking at low resolution LCD panels rather than an OLED display.
For gaming, where scenes are rendered in real-time and convergence/depth are able to be adjusted to suit the individual, 3D is definitely something I want to see more of in the future.
For films or other content where it is pre-recorded and the depth/convergence is baked into the video file, it just doesn't work for me at all. The depth/convergence for a "standard viewer" makes it look like am peering into a diorama, where everything is on distinct planes of depth, and everything just looks "small" rather than looking more realistic. I vastly prefer 2D for films, no matter what it's shown on.
Part of the problem as far as gaming is concerned is the HDMI standards. HDMI only allows for 720p60 in 3D - it doesn't allow for 1080p, so it already looks worse than 2D content for that reason alone.
And trying to run 3D on the current generation of games consoles that even struggle to play games at 720p with a target of 30fps in 2D, rather than a high-end PC, meant that most people's impressions of 3D gaming ran at shockingly low resolutions and framerates, with a lot of details turned down.
It's no wonder that 3D gaming hasn't impressed more people.
I recently picked up a 3DS XL, and that has reignited my desire for 3D. Yes, it's not perfect - it's autostereoscopic 3D with a very limited viewing angle, there's crosstalk at times, and it's a low resolution device... but after using it for a while, you get used to those limitations and only focus on the content being shown to you. When you're in the sweet spot, it's generally a very natural looking image, and 3D adds a lot compared to viewing in 2D. Even with 3D at its minimum depth setting, it's a big improvement in most games. Something I thought was quite interesting as well, is that even though the horizontal resolution is halved in 3D mode, it's actually less apparent to me that the screen is only 800x240 when running in 3D than 2D.
But I can see why people would dislike it, if the comfortable position for you to hold the device at is not the right distance for 3D, and some games handle 3D better than others. Unfortunately you can only adjust depth and not convergence on the device. And it's a good reminder of the issues that autostereoscopic 3D has - you would never want a television like this - it only works because it's a handheld device and you can reposition it with ease.
But when it works right, it's still better than any 3DTV I've used, and makes me wish they could have figured it out. They shouldn't have tried pushing 3D on us yet, and waited until it was actually ready. Now it will probably end up dying off.