An attempt to explain this ruling, found in "Vampire Grace"'s Wikia page:
The "If you control a FIRE monster, you can Special Summon this card (from your hand)." of "Goka, the Pyre of Malice" is considered to be the effect of an Effect Monster that doesn't start a Chain Link. Therefore, when "Goka, the Pyre of Malice" is Special Summoned, the effect of "Vampire Grace" in the Graveyard can be activated.
The "This card cannot be Special Summoned except by removing from play 1 "Vampire Lord" you control." of "Vampire Genesis" is not considered to be the effect of an Effect Monster. Since "Vampire Genesis" is a Special Summon Monster, this is a Summoning condition. Therefore, when "Vampire Genesis" is Special Summoned, the efect of "Vampire Grace" in the Graveyard cannot be activated.
There is a difference between Special Summons that do not start a chain.
Those monsters that can be Normal Summoned/Set and also have the ability to be Special Summoned are treated as being Special Summoned by an effect without classification. That effect does not start a chain. (It still counts as an effect though, for purposes like triggering "Vampire Grace")
Those monsters that have built-in ways to be Special Summoned but are Special Summon-only monsters (meaning they cannot be normal summoned or set but can only be special summoned by the way described in their text) like "Vampire Genesis" are considered to be Special Summoned by a condition and not an effect. (Hence they cannot trigger "Vampire Grace")
The "If you control a FIRE monster, you can Special Summon this card (from your hand)." of "Goka, the Pyre of Malice" is considered to be the effect of an Effect Monster that doesn't start a Chain Link. Therefore, when "Goka, the Pyre of Malice" is Special Summoned, the effect of "Vampire Grace" in the Graveyard can be activated.
The "This card cannot be Special Summoned except by removing from play 1 "Vampire Lord" you control." of "Vampire Genesis" is not considered to be the effect of an Effect Monster. Since "Vampire Genesis" is a Special Summon Monster, this is a Summoning condition. Therefore, when "Vampire Genesis" is Special Summoned, the efect of "Vampire Grace" in the Graveyard cannot be activated.
There is a difference between Special Summons that do not start a chain.
Those monsters that can be Normal Summoned/Set and also have the ability to be Special Summoned are treated as being Special Summoned by an effect without classification. That effect does not start a chain. (It still counts as an effect though, for purposes like triggering "Vampire Grace")
Those monsters that have built-in ways to be Special Summoned but are Special Summon-only monsters (meaning they cannot be normal summoned or set but can only be special summoned by the way described in their text) like "Vampire Genesis" are considered to be Special Summoned by a condition and not an effect. (Hence they cannot trigger "Vampire Grace")