IMHO Feathers are a time honored traditional quilting design motif. They have been used in quilting for about as long as quilting has been in existence. So they are certainly not a new trend. It is no surprise that they continue to be used in today's quilting and not just by LAQ. Beautifully executed feathers are still done by hand and also by DSM quilters. I love the look of well done feathers and I enjoy quilting them too. When I got my LA feathers were most definitely the motif I wanted to master first and foremost. Once feathers are mastered, countless other motifs can be made using the same principal as making feathers, such as leaf and vine, ferns, waves etc.
Are they being over used as a quilting motif? Well that is a matter of opinion. Just like what is over quilted to one, may be just right to another. As far as quilting all over with no regard to piecing, sometimes an all over design is just right for some quilts. I have done many that all over design is exactly what the quilt needed. And I have done others where SITD and just a bit of embellishment quilting to get the quilt to sing is what is needed.
It all boils down to preference and what your pocketbook can bear.