No one is basing whether or not they should keep a hand on Street Wraith, they're basing whether or not they should keep a hand on the other six cards. If you can't look at six cards and decide whether or not those six cards are good enough to keep a hand on, you shouldn't be playing this deck to begin with.
There's a definite reason to include Street Wraith, for the 8 cards that Dark Ritual and Wild Cantor requires, it nets an average of +1 mana with a standard deviation of 1, while for 4 cards that Street Wraith averages almost .66 mana source (which could be a Seething Song, Lion's Eye Diamond or second Right of Flame etc.) and reduces the chances of a failed Belcher activation by at least the rate of the Taiga (I think it's 17 percent if you fetch the Bayou and twice that if you fetch the Taiga). The net gain off of just 4 cards for Street Wriath is almost higher than the net gain off of 8 cards for Dark Ritual and Wild Cantor, so clearly there's a reason to consider the card.
I think it's pretty clear to any one that actually puts in the time to PT this deck that Serum Powder and Street Wraith are incredibly good cards.
Comments such as are rude and condescending. You do not need to make them and they will not convince anyone of your arguments.
-PR

