You're probably right on that particular weapon. Some of the other weapons though.... I don't know.
But you're assuming they will be updated to be the best eventually and not just updated to be "On par" with the best. There's really no guarantee that some new gear item or weapon won't create a situation where mythics aren't as good, ie. ionis zones, or when wearing some specific new armor or against new monsters or only useful when a certain trait is needed like -emnity and generally not as good the rest of the time. SE actually said something to that effect a while back when they were planning 119 upgrades.
I was more or less joking about the cooking thing, but like I said. Just because you can do something doesn't mean you will want to or that you should. It literally doesn't matter how "easy" it is. It matters if it's worth doing. Whether it's worth doing is in the mind of the person doing it. A lot of people don't like doing it. Putting the pinnacle items in your game in something that people don't like to do is just bad. Even if people don't need that item. Even if it's "Easy". it's still bad business to put it there.
Because if I'm gonna pay for a game, I want The guy with the best wits and the best skill to get things faster. I don't want the guy with the most time and the highest tolerance for tedium to get things that skill and wit cannot reasonably obtain. The game of "Who can wait in line the longest" doesn't sound fun. I mean I'm not saying there isn't a video game market for the unemployed OCD crowd who just needs something / anything to do. I just think it's incredibly small, unreliable market. SE can cater to that crowd if they want, But I'll definitely be opposed to that sort of stuff every time.
And to reiterate, I'm not saying that stuff should be obtainable in a day. I'm just saying that the amount it takes is too much. I mean lets be honest. The part we're talking about is the part that basically requires you to spend all your time shouting for people to do it. That's not even really playing the game. Even if you just love wiping the whole zone in einherjar in 5 minutes once a day or clicking lamps in Nyzul a million times, nobody likes just standing around shouting.