First, let me preface by saying thread is fucking terrible and most of you should kill yourself, numberfags first and foremost, you're worse than ennaschizo.
Answer is, aside from songs themselves being mid, it's an issue of 1)exposure and 2)output.
1)Time and time again management fucked her over. Her and her original songs, by doing absolutely 0 promotion. Usually you tease something couple weeks in advance, you post shorts, some catchy snippet from the chorus, something. Nope, when new song is out, we found out about it from IRyS saying, on some regular stream, "Oh, btw, manager-san just said there's a new song coming out tomorrow, please check it out". And the next day there will be a song. Just there. If we're lucky, it even got a bare minimum effort MV - static picture with camera panning over it and subtitles. Great, that's a sure way to promote your artist and songs.
2)She's not releasing a lot of songs. Even with that terrible management, if she released more songs, the word of mouth would get around. Like, "yeah, you don't know beforehand when the new song comes out, but it won't be long, and this girl sings really well, you should check her ou-" NOPE. EP here, EP there, couple singles, we're done, no new songs. Momentum forever lost, it's over. Say what you want about Mori, but that girl WORKS. If only IRyS had even half of that determination to plow through any shit life throws at her.
I wanted to post this in /HIRyS/ but everyone there already knows all that.