I've seen a couple butthurt posts online about how Ridley is somehow using a "bait and switch" on Alien fans - "it's not a real prequel! It's not the same ship! He played with our hearts!" Who cares? Did you really, really want a part-and-parcel, extremely exacting prequel just like that shitty Thing prequel, with more aliens, showing exactly how everything happened, as nothing more than a nice little garden addition to Alien? I would've found that incredibly boring and rote - just as I found the new Thing film.
I'd much rather see the franchise strike off in new directions - not more of the same, not just another runaround with the same monster, not some tired little yarn that is merely "this is how the ship arrived on LV-426." We have four movies plus AVP to do that. I don't know what people expected, but just, no.