Chris, There are a few issues with the current man-db setup:
1) the cache is not strictly necessary for operation of man(1); 2) mandb -c is quite slow with a large number of manpages (~20min on my system) 3) generating the cache only during man-db postinstall doesn't help for manpages updated or added between man-db releases. Therefore, we need to discuss further how to best handle the man-db cache. In the meantime, to help avoid user complaints, could you ship a new release without the postinstall/preremove? Yaakov