Here is why I think WAR may be underperforming in terms of its player base:
1. Realm vs. Realm started off slow. As of early December, there was sufficient optimization to handle battles by the 100s in RvR lakes--and some rewards to make us want to... I was there and saw a few, but by then, the player base had contracted quite a bit.
2. Community in WAR has always been weak, at least compared to WoW. When the game first shipped there wasn't even a global chat for the area you were in. If you wanted help with a public quest, say, the best you could do was yell or ask guildies for help. It just didn't lend itself to building a community, and the server transfers, while making the game playable, didn't help with the community either.
3. Strategically its PvP suffers in comparison to World of Warcraft. Though WARs emphasis is on PvP, it's funner to play PvP in WoW because it just seems there are more options, more things you can do with a given class, and battlegrounds (scenarios) in WAR are variants of get-in-the-middle-and-each-side-fight-the-other--whereas in WoW battlegrounds you have to play the map as well as fights with other players. Just more fun in WoW imo.
4. The game was poorly optimized on release with lots of crashes which left a bad first impression. They fixed most of that by December, but first impressions are first impressions.
That said, WAR has many strengths:
1. PvP emphasis: that was great, because PvP is my favorite part of an MMO. Like I said, I think WoW has more strategic richness within each class, but WAR is rife with opportunities for PvP.
2. Less BS. Things like cave camping are not possible in WAR. It was a very easy fix. Gold farmers have been weeded out mostly, and EA Mythic doesn't rely on the player base to report them. Some still slip through but they've done a really good job there. For PvE questing WAR comes with a built-in Questhelper--no trips to thottbot needed. In fact, I kind of wonder if the maker of Questhelper for WoW played the WAR beta since the two are very similar.
3. NO TWINKING!!! The simple fix was to award experience for doing battlegrounds. DUH! Though I was fairly tolerant of twinking, even though I never did it, scenarios proved to be so much more fun without twinks.
4. Class balance: I imagine this compliment will be controversial because on the boards there is no end to complaints about imbalance, but in a group with a well-distributed composition of classes, I found things to be extremely balanced. There is nothing even close to a huntard class in WAR. Most of the complaints about class imbalances in WAR, which are legion, I think come from people who don't know how to play their character and are expecting gameplay in WAR to be like another MMO. WAR definately has its own PvP style.
5. Skill > Gear. The differences because green, blue, and different levels of purple are not as great in WAR as in "that other MMO." You don't have to grind or raid or buy gold or do arena for countless hours to be well-enough equipped to be competitive.
Graphics in WAR are a mixed bag and can go either way depending on taste. Animations have a leaden quality which I actually kind of like because it sort of like little tabletop figurines have come to life. The general scenery is very easy on the eye, and sometimes almost looks like a tabletop battlefield, which I though was a nice design decision. Some animations are very poor, and the elf race, both order and chaos, needs more work.
At the end of the day...
I've never really liked the Warhammer fantasy universe, but I did enjoy playing WAR in all tiers. It's well done, ultimately though, the pvp, even RvR, struck me as bland and I grew bored.
But after playing WAR I did not and cannot go back to WoW. There is so much endless total BS that WoW players put up with daily that half of it I didn't even notice until I started playing WAR. I saw how much better it does so many things and how many abuses could be easily fixed if Blizzard were in a mind to.
I'm an RTSer anyway and the whole MMO thing was just an embarrassing diversion during a couple lean years for RTSs. I'm back to Red Alert 3 now and hoping DoW 2 and SC 2 make me never have to burn countless hours grinding again.