First and foremost, WvW is largely a zergfest. Yes, there are the videos of 5 vs. 30s with smaller groups winning the battle, but they are very much the exception. For the past 3-4 months, my guild of 3 have attempted to challenge the zerg. We have had some incredible successes, but in the end we can only do so much. We quickly found out that if you are to survive against zergs, there are really 3 competitive classes in the guerilla warfare style of combat. Thieves, Mesmers, and the Elementalist. Any other class does not have the mobility and escape mechanisms to be competitive in variable environments outside of the zerg.
Furthermore, there are very few incentives in attempting to defend supply camps. You can upgrade them all you want, you can even add some sieges here and there. However, with the possible exception of Pangloss in Eternal Battlegrounds, you are simply going to fail when the zerg shows up at your doorstep. Most commanders seem to be permanently on offense, directing their swarm of karma-frenzied pests from one point to the next.
However, all of this would be pointless, if zergs were less effective than smaller groups. ArenaNet has stated that smaller groups are much more effective than larger groups in WvW, and yet the predominant strategy by the top servers are largely mega-servers, led by Teamspeak and a commander, zerging their away across the landscape. One can ask, if smaller groups are so much more effective than larger groups, why aren't we seeing that strategy emerge more and more in WvW? The simple answer, is that they simply aren't.
But, maybe you are asking a second, more subtle question: what's wrong with zerging in the first place? Well, ultimately it requires less skill, less coordination, to execute than simultaneously placing smaller groups that communicate between each other. If you placed 40 people on a map and told them to attack point A, against 4 small, allied, teams of 10 people that each had real-time strategies to execute against the 40 people. You would expect the 4 allied teams to win? In Guild Wars 2, I would expect the 4 teams to win as well. So why aren't we seeing that in practice?
I'm not sure. It may be a combination of the systems in place, and human nature. The rewards are much greater for the average person to join a larger group of players than if he were to play by himself or with a small group. The commander system and "crossed-swords" on the map were designed to implement communication to the players on the map, and they have really just become signals of hotspots of activity. If you are in a small group, you tend to avoid your commanders. They simply attract way too much attention, and they can quickly get bogged down in long skirmishes. Or maybe it's that we are innately lazy. It's much easier simply to clump together and follow, than for multiple people to lead in diverging, strategic groups. If it's truly the latter, than there may be little hope for WvW.
Among the other main problems of WvW, progression and rewards are the other two most notable challenges that ArenaNet must face over 2013. The WvW patch will probably be released in March, and we will see how much they change. So far, it merely seems to be aimed at progression, and I'm hoping they aim their sights much higher in the coming weeks.