Firstly, they fit around my waist - and I am so not used to that. All of my (shorter) skirts sit on my hips - so these new skirts feel very weird.
Do these skirts have elastic waistbands or solid ones with zippers? If the former, you can probably reposition the skirt downwards a bit. (This is one of the reason I like elasticised waistbands and skirts with ties -- they're almost infinitely adjustable). If the latter, you have two options: The cheap one is to get used to the way the garment fits (i.e. "ignore the problem"

) or have the garment let out a little bit (if possible; many store-bought clothes don't have very large seam allowances and that makes letting them out nigh well impossible).
Secondly, to my mind they emphasize my height - and give me a drainpipe shape. Whereas (again, to my mind) a short skirt breaks up the drainpipe shape.
Emphasizing height is not necessarily a bad thing. I don't happen to recall any of the larger images, and there's not enough detail in the avatars to tell, but are you completely slab-sided or is there some "figure" to your form. If you have a narrow (-ish) waist, you might want to work with that to bust up the worst of the drainpipe look.
Thirdly, they are so big! In volume. They feel like sails - after wearing short skirts.
You took a big step with the new skirts -- bravo for doing so -- and you're not used to the way that longer skirts work. They take some getting used to, but are fully as comfortable as shorter ones; they just feel different, and part of the fun with them, to me at least, is the way they billow and move around when I'm in motion.
Fourthly - and a practical point - most of my short skirts have belt loops as they are always worn low - on the hips - so I can use a belt to hold the skirt up!
Since you're still in "experimentation mode", and since you're not out a goodly sum of cash, why not just add belt-loops yourself? They're ridiculously easy to fashion, and would be almost as simple to install -- and, since you're doing it,
you get to design every aspect.
One observation that I've made is that knee-length is by far and away the most difficult skirt length to "get right". If one misses the mark by more than a centimeter or so the look can go from stunning to dowdy. Short is easiest if one has the shape for it, and will, I suspect, be the more common mode for men if skirts for blokes catch on. Calf-length works well, too, and works on more body-types than minis do; however, like knee-length, it's possible to get a really dowdy look if one isn't careful. Very long skirts pose their own considerable challenges, not the least of which is control and management of the garment; another difficulty is getting the length
just right -- again, as little as a centimeter can make or break the look (or your leg if you trip on the hem

).
So, in conclusion, no length of skirt is inherently "better" than any other; they all require care and observation in selection and wearing, and I applaud ChristopherJ's excursion into previously unexplored territory. We should all do that a little more often.