A couple things to keep in mind. One, we were not playing on the same patch as the PTS. As a whole, the game is not running at full capacity for a closed beta. They have confirmed on the 14th that we were all playing from a centralized datacenter, and that additional hubs and agreements with content delivery networks were in place, though inactive prior to launch.
The project directors and their army of project managers are all trained the same way for a project launch. If the cost benefit anolysis of launching full resources prior to launch does not generate a revenue or value (be it marketing, sales, etc.), the it is not worth the many thousands of dollars it costs for 2 weeks of operation on a dead platform (considering the platform would be generating no value or usable information). Because of what the 'Megaserver' is, the implementation of such is one that additional servers will only add to the overall computing power/instancing/connections of the framework when they are added, and ZoS/Bethesda can get a pretty accurate gauge of what they will need to support launch.
They had over 5 million different beta applications/keys for beta. That is more than the bulk of all GW2 copies that have ever been sold...and that is just beta keys. They are promising a 'lag free' experience at launch, and have confirmed that they have agreements in place for swarms of additional server nodes to come online should they need it.
And lastly, every project director and manager is desperately trying to do one thing right now: Manage expectations in the most notoriously angry and loud demographic. If everything was smooth, then every project manager would be sweating the minor inconvenience at launch that would cost them their reputation/jobs or whatever. As a result, they are all trying to walk a fine line between bugs and smooth gameplay, knowing that they will get FAR more value from showing improvement in many areas than they would by proving their competency with a smooth game in closed beta. They can go smooth launch and let the detractors complain about the "little things" they haven't fixed, or they can show dramatic improvement and have the supporters encourage their 'progress'.