I've only skimmed a few pages, so forgive me if I am repeating anything said. Alot of the first few pages are about World of Warcraft, so I thought I would share some personal experience with it.

I've had a WoW account since pre-40 man Naxx. I also currently play(two level 90s) since Final Fantasy XIV is down.
Cross-realm in WoW is one of the biggest mistakes Blizzard has done along with Raid finder, and Dungeon finder IMO.
All three seem like good ideas, but in action they all have problems.

Cross-realm has problems in WoW because pretty much every day is like launch day, people are all over the place making questing a pain. Running into a cross-realm area in WoW also has random problems like mining nodes despawning.

Raid finder and Dungeon finder are a problem because the level of difficulty is extremely low, and people will often steal loot from others because since it's cross-realm people don't care about personal reputation. (by steal I mean healers taking dps gear, dps taking tank gear, etc.)

The community in WoW was much better when you had to form groups and interact with people on your server. Now you just que and loot.