Maybe not enough to matter though. If the input space is sufficiently smaller than the hash space (e.g., you aren't hashing arbitrary strings, but instead just arbitrary English words) then the probability of any hash collision that also lies in the realm of interest is vanishingly small.
True, but that'd be very esoteric - a string input field that only accepts values from a dictionary. Although also if the input space was only these values but the input size was infinite you'd have a similar issue :P
It'd be esoteric for a system to enforce only containing values from a dictionary, but every sentence ever spoken by anyone alive fits in a 64-bit space by a wide margin. For real-world input you could still reverse most passwords uniquely given enough time.
It's actually kind of a fun problem -- the fewer bits you have in your hash the easier it is to find _any_ collision that gives access to the current system, but the harder it is to uniquely reverse the hash into a plausible password for stuffing into other systems.
