On the community aspect, I do believe it'd hurt the community aspect of the game. The whole "hey I know that guy from x" or "don't party with x, he ninja loots stuff". Where it feels like a closer community instead of a bunch of random people who happen to inhabit the same world. Your actions make much more of an impact if you're stuck on your server and people know you from stuff like pick up groups. If you ninja loot or are a general asshole, people will find out about it and you might start getting a lot less invites to groups. With content finders that are cross-server your actions make much less of an impact because who cares? You're probably not going to see these people again and you have a shiny new sword. There's much more incentive to be a selfish asshole.
In addition, content finders work well with the type of content we have now: Spam a dungeon/encounter a shitton of times with their abysmally low drop rates and weather or not you're rewarded is mostly based upon luck. I'd like to see instances with cooldown timers of like 3-4 days but the drop rates are higher so almost every time your group runs it someone will get something or at least progress towards something. With a content finder if they do implement content like this, people will bitch about how they "got grouped with a bunch of bad players" or "so and so d/c'd" or whatever so "SE should make it so if you fail there's no lockout" or "if you use the content finder there's no lockout." or just "get rid of lockouts." People would bitch so much that SE would cave and comply to their requests because that's what the player base wants. Also "the content is too hard! no one can clear it in a pick up group make it easier QQ" so difficulty gets toned down. Then what's the point of linkshells? If you can spam content finder to get a group quickly and do the endgame content and get the best gear whenever you want instead of having to worry about linkshell schedules or if the right people are on, people will just not join linkshells and solo constantly.
Granted a lot of these reasons are implications but they're not baseless, it's happened in other games. I'd like to see FFXIV stay closer to party, group and community-oriented play instead of solo play. If I wanted to play a single player game I have plenty of choices out there, but I play this game, an MMO, to play with other people and be a part of a community.