Maybe it takes to long to clean the room thoroughly and do the towel art. I don't have the answer to that one. As to the frequency of towel art, I think it has always been hit or miss depending on the mousekeeper. We have had trips where we see towel art only on the first day and we have been on trips when there was something different each day. Don't get me wrong, the towel art is appreciated but if the staff has been instructed to spend more time cleaning the room than they did before, I will not complain about the loss of towel art.
Honestly, I don't believe it has anything at all to do with how much time it takes. When I see other posts suddenly thinking they will now have time to steam clean every inch of the room now, I just shake my head LOL.
If you have ever seen them make one, it takes seconds - since they know what they are doing, it doesn't take much longer than folding a towel the normal way for them. I think people envision it like the first time you do origami and it takes you ten minutes to make a swan because you are reading and trying to follow unfamiliar directions, vs. once someone who really knows what they are doing they can make one in ten seconds.
Disney has "discouraged" them for awhile because people actually DO complain when they have gotten them before and don't get them this time, for whatever reason. Really, people call/write to complain about them. And since not everyone knows how to do them, or cares to do them, it creates issues. It also seems to come from folks who don't see that often there is a correlation between leaving a tip for the housekeeping staff and them appearing.