If we didn't have friends, we'd play Skyrim. That was the point of ESO, so many people playing Skyrim were like, "But, I want to play with my friends!" Yet the developers of ESO seem to have bent over backwards to make it difficult for friends to play together. In my opinion, playing ESO without friends is like eating a peanut butter an jelly sandwich without milk. The first bite or two is delicious and satisfying, from there it is a chore to go on, and ultimately becomes nearly impossible to swallow. Playing with strangers in ESO is like drinking a glass of water with PB&J, while it certainly makes it easier to swallow, you will never find yourself saying, "I could really go for a PB&J sandwich with a big glass of water right about now!"
Three factions was a really bad idea. Three factions with virtually no distinguishing features was an absolutely awful idea. There's absolutely no point what so ever to the factions beyond splitting the player base into thirds, ensuring that every single player is completely unable to play with 2/3 of the player base. While you certainly need to split players up into teams for PVP, and factions is one way to do that, the factions in ESO do absolutely nothing for PVE. It's like they said, "WoW has 2 factions, we'll have 3!!!", but then stripped out every single reason behind the factions in WoW. In WoW you can travel to the lands inhabited by the other factions, in ESO you never, ever see a player from another faction outside of PVP zones. In WoW the factions are diametrically opposed antagonists/protagonists (which is which depends on who you ask), in ESO it's difficult to tell one factions lore from the next, which is exacerbated by the fact that most players can play as any race in any faction.
WoW may have 90+ levels now (I haven't played since level cap 80), and that might seem like a lot, but in ESO there are really like 150+ levels. It takes 50 levels to complete your starting faction's quest line, and then you complete each of the opposing faction's quest lines so that's the equivalent of 100 more levels and calling them ranks doesn't change that. 150 levels is a lot of separation in your player base, especially when you consider the player base has already been split into thirds by factions.
Questing/leveling is irreparably damaged by the 3 factions and 150+ levels. There's really no way to take a VR10 Ebonheart player over to the Dominion starting zone to play with a level 10, any way that would make sense anyway. However, there's no reason at all why anyone, from any faction, can't group up and play dungeons together at any time. Especially since it already works that way for PVP.
I stopped playing a couple months after launch because I got tired of choking down PB&J sandwiches without anything to drink. I tried drinking water, and while that helped, it wasn't long before the desire to log in each day completely evaporated. Here we are a year later, there's no longer a subscription, so I buy my brother a copy. He swore to never again play another subscription game, so there was no talking him into it back at launch. (I even debated paying for his sub at the time.) As a new ESO player, he's having a great time, as you would expect... didn't we all. He's sneaking off to Tamriel every spare moment, subsequently he's out leveling me by leaps and bounds even though I'm playing a well geared sorc that can nuke through quests with his eyes closed. This means more and more I find myself solo grinding quests trying to play catch up... which is the exact opposite reason I started playing again!
Of course, as luck would have it, the characters I played last year are all in Ebonheart and my brother installed, created, and leveled to 12 in the Dominion before I had a chance to tell him. Not only are my Ebonheart characters basically nothing more than crafting mules now, but now I also have to solo grind a new character just to try to keep up with my brother. If there were cross faction PVE dungeoning in ESO, I wouldn't be worried at all about "questing" with my brother, because I could play my Ebonheart characters with him in dungeons, which are by far my favorite part of ESO anyway.
Ideally, the developers would read this and immediately assign a crack team of coders to implement cross faction dungeoning with player level scaling by next patch. I think we all know that's not going to happen, just as I think we all know it will more than likely never happen at all. I have a compromise. A cross faction Veteran Rank PVE Zone with quests and dungeons, with ALL PVE content from hence forth being added into this ever expanding zone.
I just want to play with my friends, is that so wrong?