It is a load of bilge, so much so, it makes the first film look half competent. I laughed when the Strause brothers blamed the studio for all the bad reviews the film was getting, and said their next effort 'Skyline' would show what they can really do. Not a lot as it turns out, because that film was equally as bad. SFX guys shouldn't be directing films. A former ILM SFX supervisor directed the comic book film 'Spawn'. That was also a stinking turd of a film. Stick to SFX, guys.
A 'balls to the wall' Alien/Predator film would be great, but that's not likely to happen sadly. Studios are more interested in putting 'bums on seats'. Look at the upcoming family friendly Robocop film. There was no way in hell it was going to get an R rating, not when so many kids will want to go see it. More money for Hollywood bosses, and that's all that matters (to them at at least).
As for the Aliens being dependent on their hosts; the reason for this is that this allows them to adapt to whatever to environment they are born in to. Giger's original only came from humans, so we are used to seeing that specific design.