I'm going to join everyone else and disagree with you. I think you're the one being short sighted on this one. Ifrit's bonuses are fantastic for a melee set up. I think you're fixating on the current preference for rangers on some of the more difficult content, and therefore you want our buffs to benefit them. There is still plenty of content where you will have Monks, Samurais or other melee jobs. We already have favors that would benefit mage jobs. You can't honestly think that Refresh, Regen, MAB, Evasion, etc. bonuses are what will get summoner a spot in a party. You are also very likely to have a Bard in your party to provide accuracy songs if needed, so I think it is in our favor to have unique buffs like Double Attack or Crit Bonus.
As others have explained, the reason why no one asks for these favors is not because of the buffs themselves, but because of how horribly implemented Avatar's Favor is. These changes could be a huge step in the right direction. Removing the penalties to the avatars is necessary and a huge step in the right direction. There are a few key points that I really hope the dev team changes.
1. The favor absolutely cannot be reset by blood pact usage. For me this is the main issue. If you want the SMN to be worthy of the party slot, they are going to have to be able to keep the Favor at full potency AND be able to use other Ward or Rage pacts to assist the party. This really is non-negotiable. With the increased perp cost, I don't see this being remotely overpowered.
2. Maintaining the favor after the avatar is defeated: I'm not sure if this is possible, but the avatars will be taking heavy damage because they will be in melee range. If the favor is reset every time the avatar is defeated, it will be very difficult to keep the favor at max potency. If this cannot be programmed, then the ramp up time needs to be greatly reduced OR the base potency of the effects should be raised. Another alternative would be to greatly increase the range of the aura so that the avatar can remain on the back lines with the Summoner.
With those two items and the removal of the negative effects on the avatar, I think we'll be a job in contention. There are a couple of additional tweaks, like increasing avatar subtle blow and allowing the avatars to receive the favor themselves that would be greatly welcomed. (The latter would also help to further specialize the avatars. Elemental correlation would still remain paramount, but I think allowing the avatars to have their own mini specialization would add great fun to the job.)