Server capacity does not necessarily mean number of servers.I thought the problem was the code & not server capacity?
I suspect database (low) performance and (bad) scalability is what hurt the game at launch, and still does a bit now on rush hours.
And you cannot really just throw new servers into the equation to solve this kind of conceptual problems, they need to rethink a lot of things, to rewrite some client and server code, etc, and all this takes a lot of time.
Given the massive influx of new players the PS+ edition will lead to, they better be safe than sorry.