I think we all can agree on server hopping being a real issue, but not a main one. Pretty simple fix to do.
The "lock people out of WvW for a week after they transfer" idea seems so simple and elegant that it baffles me that they haven't done it yet. Maybe they think it will hurt too many players who are server hopping for legitimate reasons.
Obviously the main problem is there is currently a real lack of come back method. People log on, look at the pie, see they have jack shit and leave it at that. Even trying to do something is futile because there's probably a handful of people in wvw. 2v1 doesn't work because there's incentive to actually do it and how the fuck do you logistically plan it anyways?
IMO they need to attack this from two (and maybe three) fronts:
1) Player motivation. If you're getting stomped, WvW can be a net loss since your repair bills will outweigh any gains you make. The current outmanned buff doesn't really solve this.
Getting rid of repair bills in WvW would help. One thing I'd like to see is
increased armor damage (say, each death = one broken armor piece) but free repairs. This would make it easier for a small group to thin out a zerg by forcing them to go back for repairs more often. Small groups who get wiped would be unaffected (since they're respawning anyway), but it would slow the momentum of zergs because the consequences of letting people die and get rezzed after the skirmish would be much higher.
If they want to stick with the current "outmanned" concept, I'd suggest reworking it into an "outplayed" buff as well (so it also applies when your server holds <2-3 points on a map). And it needs to be massively increased, to the point where retaking that first tower/keep becomes the most lucrative goal for your server, moreso than DE farming/dragon fights/etc. If players have more attractive rewards elsewhere, they're not going to hop into WvW to piss away money on repair bills. It would also be cool if these were periodically broadcast into the PvE game -- "Your server needs your help establishing a foothold in X Borderlands! Retake Bluelake Tower to earn Y reward!"
2) Make 2v1s viable. It seems like this was a big part of Anet's plan to keep things from getting too one-sided. But in practice it turns into a sort of prisoner's dilemma where the two losing servers are better off squabbling between each other, because if one of them turns their attention to the #1 server, they're opening themselves up for attack from the other underdog. On top of that, there's no in-game mechanism to facilitate cooperation, so players tend to kill all enemies on sight just to be safe. Something as simple as increased karma/gold/badge prizes could be used to nudge players into pressuring the dominant server.
And finally (maybe just as a last resort),
3) Meaningful in-game mechanisms to benefit the underdog teams. Based on the current state of the outmanned buff, it seems Anet wants to avoid giving the underdogs gameplay advantages, presumably to keep the rules fair and prevent the Mario Kart syndrome where it's too advantageous to be in last place. But the current rules swing too far in the other direction -- dominating a map gives too many advantages (orbs, increased supply, map control) so large comebacks are rare to nonexistent. This is why "night capping" is such a problem imo, because taking a whole map at night swings the momentum dramatically more than is ever realistically possible during peak hours, so it's often irrecoverable even with a good peak hour team.
I think there are some creative ways to attack this without falling back on "the losers get extra HP/damage". One cool suggestion I read was to have a neutral boss NPC that can show up to harass a server if it becomes too dominant, which would force them to pull back and fight it before it drains their supply (or eventually destroys upgrades if they ignore it too long). Other systems like that could provide more opportunities for comebacks, without being demoralizing for the leading server.
Anyway, I don't want to make it sound like I'm crapping on WvW too much here. It's still a ton of fun when it works, I just hope they can work out a solution to all the one-sided blowouts.