I think after Aliens, a lot of people, myself included, were expecting the 3rd movie to be even bigger in scale and be a direct continuation of the second movie, and focusing on what happens when the Aliens finally make it to Earth. It was also expected that the 3rd movie would continue to feature Hicks and perhaps Newt together with Ripley, struggling to escape an Earth rapidly being taken over by the Aliens.
Instead, the 3rd movie was a step backwards in many ways, being much smaller in scale and directed by at that time a 'no-name' director whose only experience was pop-music videos IIRC.
Graham