A game with no remixes does not always equal an unpopular or little known game, Kyle. You've been around here long enough to know this. It's a Turtles game, on the SNES. It's well known, as is its music. So why no remixes? Simple... no one's felt the need or inspiration to do them. Popularity only goes so far in deciding what will be remixed. A bigger part of that process is what sparks the idea in you... what makes you think "This would sound cool if I did this and that and those." Sometimes that spark comes from a song being on an old system with it's lower quality sound capabilities, sometimes it's because you can kind of hear the genre it's supposed to be in but want to enhance it or change the genre entirely, and sometimes it was just a song you really liked and wanted to tinker with. Of course, no one will hear anything around here if it's not up to OCR standards, will they? Or if the remix doesn't get done. Or, and this is from the old VGMix days, if they choose a different game because it's even more popular and sure to get more people to listen and submit reviews. There are 1,000 reasons why there aren't many TiT remixes, but it's soundtrack not being well known (especially around here) is not likely chief among them.
To me, Turtles in Time is a game that many like, but nearly no one's bothered to remix... kind of like Demon's Crest, Axelay, MechWarrior 2 and even Castlevania: Symphony of the Night. We all know the songs and enjoy them, but few ever say "You know what? I'm gonna remix that tune!" when they play the games. As such, TiT's one of the Susan Lucci's of the gaming world... always talked about, but rarely given that special extra bit of recognition.