First off a MMO is on a much larger scale than an Indie developed game there will always be bugs hell im betting at least 2 months down the road a few more might just show up out of nowhere.
You can never fully prepare any MMO to release without any problems.
Was doing Early Access on the Weekend a bad thing? Maybe. I doubt they have as many people in Customer Support as they would for "Normal Business hours".
If you seriously Pre-ordered just so you can play during the "Early Access" you have never worked on an MMO project before.
(PS ive done some work on Ragnarok Online Their code is awful)
Expect a lot of downtime fixing things square hasn't really been on top of the MMO market, even World of Warcraft took a very long time to figure out how to deal with running an MMO. (And activision is trying very hard to ruin it in every way)
Give them some time and support good games are not release date gems, they are usually worked on and improved by the company as often as possible long after release day.