An interesting angle... Digging it up again because I think I can add something.
My first thought was something others have already mentioned: the "created by an intelligence" hypothesis simply makes much more sense for crop-circles because we can readily identify good candidates for this "intelligence": human pranksters. They are around in abundance, they have the (proven) ability to create circles and the (proven) tendency to create pranks. We do not have as easily an "intelligence" candidate available for something that looks like biological design.
Secondly, and I haven't seen this pointed out, the "intelligence" that is being displayed in cropcircles is different from apparent intelligence in biological systems in that it is "non-functional". Crop-"circles" are intriguing because they show geometric regularity, but this fact and its complexity have no identifiable "purpose". This while the reason for claiming ID lies in the observation that everything "works so well together". That there seems to be "purpose", "intent" behind it all. And also that it "couldn't have been much different". There is no such requirement for crop-circles. A completely irregular cropcircle is just as viable and possible as one that shows a complex fractal. The property that makes it look like it was created by an "intelligence" is not necessary. Or still expressed in another way: its "design" stands completely on its own. It is not intertwined with the environment, guided by the circumstances in which the crop-circle exists. It doesn't have to respond to pressures of any kind, it doesn't have to fit into constraints. Well, this idea is actually harder to express than I thought, lol I hope you get what I mean.
Imo, therefore the axiom that a new paradigm must come along to replace the old paradigm, before we determine the old is wrong, is false, and leads to ignoring unexplained data and trying to fit it into an old paradigm, which is also wrong and unscientific.
Good science should therefore not dismiss any hypothesis based on a a lack of technological ability to measure and determine if it is true because if it does, there is a high likelihood of drawing false conclusions.
Some crop circles have been discovered to be hoaxes, but the people researching this stuff claim some others do not appear to be. Frankly, I have no idea, but it would not surprise me if some crop circles appeared that were not hoaxes, and then people got into the act and started using the phenomena to create hoaxes.
That's happened with UFOs. There are extremely credible UFO reports such as the 1947 appearance of UFOs visually and on radar over DC which resulted in multiple scrambling of jets. But there have been hoaxes too, probably once the idea got out and some pranksters wanted to have a little fun.
Of course, the thousands of people that witnesses the UFOs over Washington and the military scrambling jets to intercept, the pilots first-hand reports, and the radar signals were not hoaxes.
It never ceases to amaze me what some people will and won't believe.
UFO's? "Sure!" Paranormal powers? "Absolutely!" Ghosts and haunted houses? "Beyond a doubt!" Government conspiracies? "The truth is out there!"
The scientifically mainstream position, supported by the evidence, that natural processes suffice to account for all life on Earth, including us? "Woah, hang on there. Isn't that a little far-fetched?"
the cause of which we have not always fully observed and therefore do not fully understand, and yet we can seem to agree that an unknown intelligence has guided this process. And this conclusion does not seem to be criticized as being unscientific.
Actualy it has been observed It was tested by means of a wooden plank some rope and some geometry skills crop circles where made that where identical to the ones seen And it is the most logical explanation that accounts for all the facts and all the evidence.
So it is scientific to say an intelligent human with a rope and some geometry skills and a wooden plank made the circles.