So why are the crafter relics.. bad.

[Gemina]

The TLDR from this is 'if you manage to hit a good on IQ2+ then the relic is better, for expert recipes'.

Now how many expert recipes are there in Endwalker, since pre-endwalker recipes can just be brute forced via macros.

Is the relic perk actually worth the small niche use that it gets used for?

Like I said before, you need to overmeld your tools in order to actually gain anything, particularly with the control stat. And you lose one of those slots if you decide to meld CP in order to negate the loss of the +7 stat from the crystalline tools. You also need to keep in mind that not all players are in i620 gear, and the relic tools will undoubtedly help the ones who are not get there.

Another thing to keep in mind are for the players who have put in the effort to craft and pentameld their tools. Do you really think it is favorable for a first stage relic tool to just wipe out that effort?

As for expert recipes, the value of doing those recipes is up to the player. I would wager most crafters don't even touch them, and the crystalline tools can encourage more players to try them without enduring the expense of pentamelds.