It doesn't matter if they do put servers in SA other than a bit better latency.
It matters enormously - There is a huge difference between 190ms and ~30 (we'd be able to play in lockstep mode).
They can hardly support their servers already in production.
It happens they've just announced
server-side performance improvements and to be honest, as someone playing since 2013, each release has gotten better in terms of queues and handling player numbers, etc.
The Performance of the game has deteriorated further after each patch release, there are hundreds of support threads on the forum complaining about poor FPS/ Poor network performance from various area's across the globe. I my self have been privileged to play from SA, NY and London on various different specification machines which way surpass the requirements & I am having the exact same issue. I think it boils down to lack of routine maintenance and shoddy network code/lack of texture prefetch function which in itself is something they stated they are working once since early patches.
In my experience, performance has increased, in an almost miraculous fashion, over the years. I do suspect though, that some of the performance issues are possibly hidden by the fact I am already running at SA latencies. But don't get me wrong - That there are issues, I don't deny, but for me, there's absolutely been improvement in this respect on every front as time has gone on since I started playing.
The game is addictive and I love it to bits but rather focus on quality experience than constant content creation.
I absolutely understand in theory, but from the horse's mouth:
https://www.reddit.com/r/pathofexile/comments/7tni2t/our_upcoming_development_schedule/dtebqt9/