After doing a bit of wikipedia research, I concede that you are probably right regarding fullHD. Apparently LCD displays first outsold CRT for computer monitors in 2003 while for TVs it was in around 2006/2007. Now, I do recall sub-fHD resolutions being the rule rather than the exception for a long time in computer monitors while TVs basically came in 720p or fHD from pretty early on. So it is logical to assume that TVs used fHD widely before monitors did. But, like you said, that is of little consequence.
As far as 4K TVs are concerned, I hear your argument clearly. But what will play a huge role, in my opinion at least, is the availability of media. Computers will have games that support the 4K resolution while you probably would need to replace you Blu-ray player and then choose from a small catalog of titles at first to utilize all them pixels. I'm not convinced people would go for it in large enough numbers.
But if I'm wrong, it won't be the first time. I also predicted that HD-DVD would win the high-def wars
Before the Xbox 360 and PS3, TVs were moving to the 720p/1080p standard while computer monitors were aiming for 1200p for compatibility reasons, because it was easier and cheaper for them to jump from 1680 x 1050 to 1920 x 1200 and because they had DVI already. 1080p had actually been doable for a while before then on professional monitors and some Sony 4:3 units, but that's a market cut off to the public entirely.
The change came about when laptops began outselling computers. The web was shifting to a wide-screen 16:9 ratio at the beginning of 2005 and companies making TV and monitor panels collapsed and were absorbed by one another. Sony made the move to 16:9 to keep its factories running without conversion losses, LG moved to 1920 x 1080 as well for compatibility and pretty soon the entire industry was going for panels aimed at a 1080p resolution because they could get more panels out of the same sheet materials.
Professional 4K monitors and the Seiki 4K TVs that are being sold in the US now use an upscaler and interpolator for 1080p viewing. It only works for video AFAIK, but it gives you the same benefits and works in a similar way to Apple's Retina displays. So that means that compatibility isn't an issue - upgrade your TV, plug in your HTPC/console/Blu-Ray player and get crisper images without upgrading the rest of the pipeline. When you're ready for 4K, you've made your TV purchase already - that's how I think its going to go down.
The companies making the push into 4K will be Sony, Samsung and LG. The ones actually delivering the content will be Sony, Samsung, Apple, Yahoo (assuming they do buy Hulu), Netflix and Amazon. The ones with the hardware for 4K playback right in the beginning will be Intel (with NUC-like devices), AMD (APUs and HD7000 series handle proper Blu-Ray and 4K playback wonderfully) Sony's PS4, the Xbox One and whatever Blu-Ray 4K player Samsung puts out - or alternatively a Smart 4K TV.