I always look at spectres as immolation foddor that can grow if I need it too.
It's interesting that nobody else has pointed this out, though I think Antagon hinted at it. In a rush deck using immos, a 3 , 2 attack creature is not necessarily better than a :2 fire, 0 attack creature.
I'd much prefer Spectre to be 2 and 2/2, so it essentially just gets one "free" blaze for being upped. As is I'd consider putting unupped Spirits in an otherwise fully upped deck.
Out of curiosity, can I get a deck code that uses Spirits as Immo fodder? Never built Immo based deck with them myself.
On topic, fire has flies, pheonixes and free cards to immolate. I really dont see the need to make more creatures good immolation fodder. Its asking for fastest decks to be even faster. I never saw Fire Spectres as a rush card either (as it starts with 0 or 2 attack), so I'm not following the reasoning here why would it be so important to make them faster than they are.
However, I do agree that Spectre could use a buff. Maybe it is because Fire has other insanely great cards, or maybe it is because they are weakish, but I dont use them much in my decks. However, I'd probably buff their HP, to make them more durable, instead of increasing their "speed".