I am completely following you on this Mike, and find your perspective very interesting and well thought out...however, I just don't find myself convinced. I'm not one to call any irregularity a genetic defect, as so many morphs are well suited(color/pattern) for living in the wild. Your suggestion of spiders taking a different evolutionary path could only be determined by surveys and statistical data. I don't think that them being found in the wild is enough to go on, as many of our morphs came from the wild.
Although it may not be a worthwhile study, it would be an interesting one for sure...to survey spider bp populations vs. normals/wildtypes/various other wild morphs, see if there are any differences in prey of choice between them, etc...
All that said, I like spiders, and I don't mind their wobble. They are fascinating on their own and make incredible combos...the wobble, be it neurological defect or evolutionary gain, is part of the package, and I don't think people should let it worry them to the point of choosing not to work with spiders because of it.