It's more exciting, and it makes the weapon feel more like a trophy that you got during an adventure instead of being something that you literally bought using special coins that you get by killing the boss 20 times. Which just makes it feel like a cheap piece of plastic. And having to go there exactly 20 times makes it feel like a job instead of an adventure. As someone put it in an earlier post, "mindless grind".
Although I must point out, the same is not true for crafting. If I mix bread and cheese, I expect a sandwich 100% of the time. The Mystic Forge is bullshit.
The thing is, there are so many games I'd recommend instead of GW2, that there is no group of players that I feel it would fit for.
One interesting thing about the opening post is that it is a list of some of the things that GW2 is/was praised for, and an explanation for each of those things as to why that praise really was undeserved.
But MM necro is a viable way to play the game. You can roll that build, bring it into a dungeon, and successfully complete it. It's just not optimal.
Viable is just another word for optimal. Unviable is just another word for crappy. You can complete almost any part of the game with a totally random build, I mean one that isn't even a concept build like MM but just random trait settings and random skills using a random weapon. It's "viable"? Not really, not if you want to allow the word "viable" to mean something.
There are already professions that cover each other, so I see no problem in adding yet another. I feel that importing the ritualist profession from GW1 would be a good idea, or maybe some sort of bard-ish profession.