I'm fine if open world mob grinding is an option. I enjoyed it in FFXI, so why not. Unfortunately, the majority of the community has always been of the mindset that there is only one way to do things. Whichever method gives the most exp per hour (or is perceived to do so, whether it does or not), that becomes the cultural norm, and just like religions, it generates the zealot mentality of "only this way is right".
I'm definitely in favor of options. FATE parties are fun really late at night when fewer people are on, and I wouldn't want them to go away. But not finding parties for dungeons sucks, especially since that is how I would prefer to exp.