He has all the needs to be one: tragic backstory, spider-powers, cool costume, good redemption story, but still…
I my opinion, those are the reasons:
1. He is connected to the (mostly) unpopular Clone saga.
2. At the same time, another „dark“ spider came out: Superior Spider-Man
3. Will always be in Ben Reilly`s shadow
4. Authors did not use him properly
5. Too many spiders around!