Compared to 1kws they are much more efficient and put off way less heat. A few cycles and they could potentially pay for themselves in the savings depending on your set up. There are a ton of variables, but looking solely at heat vs light output, LEDs can be competitive with a traditional 1kw HID set up. I'm not an advocate of LEDs myself but know people who have had quite a bit of success with them so I can't say that they are worthless, but the industry seems to currently be leaning heavily towards 315 CMHs.
Apart from just heat and energy consumption, PAR output is another thing to consider. A lot of sources claim that many LEDs will have a much higher PAR rating than an HID of the same wattage.
Like you said, it's debatable and unless you could provide factual evidence that would substantiate a claim that they are worthless, there are a lot of arguments to be made for them and a lot of applications they may be useful for as well, particularly a small grow where heating and cooling is difficult and a small canopy is going to be grown.