To be absolutely fair though, SE COULD have rewritten a lot of their login and queuing processes to "future proof" the game. Things could have been better but most of the people ranting are "Hindsight 2020" ragers. SE has many opportunities for improving the game purely from a software point of view, but it takes something like the current situation to support the need for that level of rework, at least to the higher ups who need to approve the costs.
It was all working for most of the users and the dropped queue errors usually went away relatively quickly after initial rushes.. this release is all kinds of firsts for them though.
I think in the current situation though they ARE doing all they can to react. The new patch should fix some of the 2002 drops, especially to those who drop simply because of poor login server queuing processes and they have announced some pretty radical changes to their upgrade plans, with heavy chunks of capacity being approved and being worked towards implementation as we speak.
There are always things that COULD have been done, but there's very little I would have expected to be done personally. Companies don't like to spend extra money for no reason and there was very little reason for them to get all ambitious 3 years ago. Also being so close to a release of an expansion I wouldn't have expected them to rework basic things like the login process or server interactions when the focus for the last year has likely been refining all the new stuff in the game itself.