Do Relic, Mythic, and Empyrean staves lack utility?

[Alhanelem]

Its easy for a WAR to go from doing 10k Ukko's Fury to a 4k Ukko's Fury, and still have a decent DoT rate.

Same for SMN. The whole point of the weapon is the higher DoT. Staff is not about its weapon skills. But you also have an avatar up doing its own melee DoT and the periodic spike damage.

and by the time you are able to get 300% TP, you would have less than 10% of your MP, if at best!

My personal experience declares this false. If you can't keep your MP up from one TP to the next, you're doing something wrong. And even if that's the case, you still have elemental siphon to fall back on.
Offensive gear in the visible gear slots is pretty limited. So you can keep most of your perp- and refresh, and favor the rings/earrings/back/waist/neck/weapon/grip. Additionally, Myrkr's mod is max MP (effectively), and with your usual SMN gear mostly having lots of MP on it, you will have it on for that. If you are using up more than 60% of your MP in the time it takes to build TP, you're doing something seriously wrong.

You can exercise your right to not use this playstyle, but I will exercise my right to say and prove that it is a useable and viable playstyle.

Everytime I see a Claustrum my heart sinks knowing all that work went into a weapon that practically will never be used outside clowning around.

Anyone who builds one of these weapons is not "clowning around." They are among the most serious and dedicated about their job. Besides, it is their right and privilege to get whatever weapon they want, who are you to tell them it's wrong?