Do Relic, Mythic, and Empyrean staves lack utility?

[Alhanelem]

For example, teach me how you would melee solo something as easy as Aggressor Antlion.

I probably wouldn't use that method on it only because I would need to give up the best atmas for the situation to give the avatar enough survivability. This doesn't have any relevance to what you or I wrote though, so I don't know why you brought it up. Stop acting like I would melee everything. I don't. I use it where it is reasonably possible to do so. And there are many things where it can be used. If an NM doesn't hit too hard such that you can resummon without getitng interrupted (Not too hard when you have well over 400 skill and Aquaveil as well), it can be done.

Ok, so, an instant cast MP recovery job ability, coupled by just either a few cures or a Lucid Potion II, is worthless compared to a WS that gives just as much back, but you have to get 300% TP to do so?

Yes:
1)again, convert has a 10 minute recharge. It's not instant, except for the first time you use it.
2)You have potions, but so do I. And potions are only good once until you go get more.
3)You don't have to wait for 300% TP; doing so is optimal because it gives you the best aftermath bang for your buck, but it's hardly a requirement.
4) Myrkr at 300% potentially gives you back just as much or more MP (much more if you're Tarutaru) as convert but takes far less time. Myrkr is more efficient than Convert, end of story.

I'm not against you, but you seem to be taking a Dallas approach when it comes to people pointing out some flaws in your argument.

I'm not taking a dallas approach. I put the requisite thought into this and I'm not just spurting extreme statements with no basis. The proof is in the pudding.