A prequel would have been a smarter choice
Although the first one was the critics' darling, many viewers had complaints about the weak plotting. A prequel might have given us some important answers such as:
i. Who the hell builds stairs with the nails STICKING UP?
ii. One newly widowed Mom figures out how to kill these creatures despite their apparently indestructible armour. How come the entire might and minds of the military and government were unable to do the same?
iii. Given that one daughter was deaf and one of the other kids was barely past being a toddler, what happened previously to make these parents so stupid as to take these kids with them on a shopping expedition?
iv. Why were no condoms or birth control pills available to these parents because who doesn't want to bring a new squalling baby into a world ravaged by powerful super-predators with super-hearing?
There are many other questions that should be answered but I'll leave it to others here to add to my list...