they have done plenty of stress testing, and we have no service level agreement. Its 2014 and we are paying a subscription for access to an online service with no guarantee that we will ever have access.. The rest about how WoW and other games coped with this is just excuses. SWTOR had almost zero downtime for the first month, they only had huge maintenance periods.
Hardware resources are cheaper and more powerful than 10 years ago, just compare the cpu's of that time with the cpu's of today, day and night power wise and core wise.