Long answer http://www.pathofexile.com/forum/view-thread/889669
Short answer - No, it isn't intentional. It is the side effect of their server/client interaction. There are ways to mitigate it via playstyle once you learn what causes it. Quartz flasks are your friend, they let you move through monsters.
Basically what is happening, is you are trying to move away before the monsters spawn and on your screen, you've done so. On the server side though, you got stuck with all the monsters you couldn't move through. You think you are outside of them, but really you are inside the pack getting wailed upon. The server then resyncs you and you appear inside all of them(Which is where you were all along). You then typically, die horribly. This is most often caused by trying to run through packs of monsters and tight spaces, especially running from monster spawns from opening boxes.
If you want to open boxes safety. You should use a smoke mine to teleport out after opening it, use a quartz flask to let you move through monsters, also lightning warp well timed can work as well.
Basically, you can mitigate this problem, once you understand how it works.
Whoops, my short answer turned into a long answer. Oh well.