The reason is avex is not paying US+EU DJs anymore (That was clearly noticeable with ayu-mi-x V and that explains the lack of remixes lately), H/\L has become weaker and they only have been relying mostly on the "Dub's" remixes. The lack of songs is not a reason though because how many remixes do we have of Free&Easy and Real me? How many remixes do we have from RAINBOW (the song)? blah blah blah There's plenty of songs lacking remixes and that could still have some work done on them.
