The problem with Alien 3 was that it wasn't a logical progression. From Alien to Aliens we had more action, more adventure, a little more of the xenomorph mythos and a little more of the Earth stuff.
Alien 3 was nothing but a return to Alien. There was less action, less adventure, less mythology and less Earth stuff. And also the characters from the previous entry were written off.
It became more instead more scary, more intimate and more painful, even more than Alien. One can argue it was a step backwards from Aliens, others that it returned to the original Alien feel and heightened it.
Alien 3 could have escalated into something even bigger: More of the xenomorph mythology, more interesting characters, more Earth stuff, more actio and adventure... I think that's what Blomkamp wants to do.