What can we learn from Diablo 3 & and open letter to Blizzard

With all the hype about Diablo 3 as of late, it's been plagued by several issues.  What lessons should Blizzard take away from this?  In my book, plenty.
The Diablo universe is one of the biggest PC gaming franchises from the 20th century.  Millions of people worldwide lined up for the midnight release.  And these millions of people go home, install their game, and see this:

Millions of Blizzard's fans effectively coordinated a Distributed Denial of Service attack on the Blizzard authentication server, without even making it an attack.  The Distributed Denial of Service attack is a popular too of a rather well known group: Anonymous.  Yes, Anonymous used the DDos to take down multiple websites during Operation Payback. Other hackers used it to take down the Assassin's Creed 2 Authentication server on the PC. 

(Note: this next part can be considered an open letter to Blizzard)

Blizz, you guys know better than this.  You were able to handle the rush of millions of people logging in to World of Warcraft every time you've released a new expansion.  I highly doubt that 20 million people fired up Diablo 3, and you don't have backup servers available that could jump in to alleviate the stress.  Heck, when CCP games heard about the plans to "Burn Jita," they put the Jita system on their biggest server they had.  They knew they had a shipload of traffic that would be going to a single server in a short amount of time. (14,000 Thrasher ships? Holy %&#$...)  They reacted in an appropriate manner.

Now, if you know you're going to have a ton of traffic on something big, why wouldn't you put your biggest, beefiest server on the front line to soak up the traffic?  What would ever possess you to ignore something like this?  Your open beta stress test should have given you an insight into what was coming.  You should have seen this coming.

Also, like I said before, I'm all for companies protecting their intellectual property.  But by moving the random map generation and loot drops server-side, you really make things difficult for yourself down the road.  Then again, what's happened thus far should make this obvious.  What happens when your customers want to play the single player campaign in 2035?  Are you seriously planning on keeping that server online?  Are you prepared to take on the financial burden?  Are you going to rely on pirate servers that "illegally" modified your source code to redirect to a different server?  Warcraft 2 battle.net Edition doesn't require much in the way of server-side computation.  Nor does the Starcraft series.  Keeping those servers online is chump change for a company of your size, and I applaud you for supporting 15 year old games.  You're a standard-bearer in that regard.  But having your server run constant calculations for your end users requires a much more powerful machine, and I'd go so far as to say that you'll need WoW-class servers to handle it long term.

Blizz, you have a high standard of quality, and it's shown time after time.  The communities you build around your games are huge, and with damn good reason.  That's why it pains me to see you making mistakes that, in all honesty, you should have learned from others.  This isn't like you, Blizz.  You could be doing so much better.  I'd wager that there's an epic awesome game down there, just waiting for people to play it.  But the bottleneck you've inadvertently established is tarnishing the polish on what could be a f***ing epic game. I hope you get it worked out, and soon.