It’s not for you to judge what’s right and wrong. You can have your own opinion but that doesn’t have to be the correct one.
And none of them are real reasons, as dual specs won’t bring that problematic:
I don’t know how open world content would become easier. You have your raid spec and your pvp spec or dungeon spec. Or you play healer and tank. A spec for farming? Well, maybe, but it won’t change as much for them. I don’t think you would farm a lot faster compared to your raid spec.
Only exceptions are maybe tanks and healer, but do we really want to punish them for playing the important specs in raids?
One of your arguments was, that gold is already farmed very fast etc. When people really want to min max for the content, because they can’t get it cleared without, do you really think they won’t min max right now as well?
There are also work arounds for it. Dual spec only in major cities usable. Raid IDs are locked to the specialization you killed the first boss with and so on.
Ehm, There was a guild that leveled from 60 to 70 and cleared stage 1 completely in less than 24 hours. I don’t know if you can burn any faster through the content.
And hardcore raid guilds who want to burn through the content will anyways, as they can min max the talents for each encounter anyways.
So for the last time: Dual spec doesn’t bring more possibilities to the game, it just removes the over extensive gold costs if you want to enjoy more than just one content.
It saves the time for some gold farming that can be invested into other content the whole game benefits from. More tanks/healer for dungeons (it’s not solving the problem, but no matter what, it’s better with than without), More people who queue for arena. More PvP player who participate in raids/dungeons. And so on.
Probably because they weren’t even worth it to discuss about.
Last but not least: HOW does all of that have a negative impact ON YOUR gaming experience? I don’t get it. Why do you care about how fast others get through the content? Or if they min/max?
Your reasonings are nothing else than an opinion. You maybe don’t like that other guild are rushing through the content. But only because they rush, doesn’t mean you have to rush. It doesn’t affect you at all! When you go for a walk in the park, it doesn’t bother you that a group of cyclists or joggers make their rounds much faster, does it?