Ok yes it's expensive and it will use up your Fractal Relics very fast if you can't wait to reach "Fractal God."
But it's not a long term solution, because eventually you will reach T4 and then the problem will start all over, not to mention you will recieve additional Fractal Relics at that point, so instead of solving the problem it will amplify it. It's the same as when the Infinite potions came out, I didnt have enough relics for all 3, but I sold some of my Pristine Fractal Relics and bought the whole lot in one go. Then came out the Omnipotion for which the previous 3 were required + 5 Gifts of Ascension, but by then I already had more than enough to buy all 5.
So this is pretty much the same, we spend all Fractal Relics on these upgrades and after that we return to accumulating truck loads of them.
I mean if I wanted to I could reach T3 right now, I would just have to buy all the required Infusions on TP, but I'm in no rush so I won't.
I have a better solution to the problem and it's a very simple one:
Give one of the Fractal Merchants another option where they sell +1 Agony Infusions at the price of 1 Fractal Relic per Infusion.
Now someone may say that's too cheap but keep in mind you need 256 of them to get a single +9, also remember we still have to pay the cost of Regents to make them.
And it would actually slow down the process of reaching T4 because it would use up a lot of Fractal Relics just to make the required Infusions.
A +16 alone requires 32768 +1's to make, while all 4 i.e. +13, +14, +15 and +16 would cost a total of 61440 +1's.
So yes it would drain Fractal Relics very fast, not to mention it is a long term solution as even after reaching T4 you could use the ability to buy +1's to Infuse other characters faster.