I think that EoS's lack of notoriety can best be attributed to the following factors:
1. They were signed to Black Mark, which hardly promotes and distributes it's bands in the same manner that a label like Nuclear Blast or Century Media does. This is the reason that bands like In Flames and Soilwork, which were both mentioned, are more well-known and discussed throughout the world.
2. Edge Of Sanity was never a big touring act, and they never once made an appearance in North America. They didn't exactly shove their names into the faces of people all over the world, either because of a lack of funding from Black Mark or, as I would suspect, that many of the members (especially Dan) were involved with other musical projects, and in Dan's case, dozens of them!
3. Their peak period (from
The Spectral Sorrows thru to and including
Crimson ) came at a time when death metal's popularity was starting to wane somewhat during the so-called "Grunge" craze, after it's booming popularity of only a couple years before that. With the popularity of Opeth and bands of their ilk nowadays, if EoS would have released
Crimson, for instance, in the past three years, they would be the most talked about metal band on the planet right now. Their experimentation and innovation went completely unnoticed at the time.
At least I think those are the most important factors. There are likely numerous others, and it's really too bad, because there will never be another band quite like em...