Combinations of simple tags are useful to categorise a feature (rather than single tags with complex meaning). It's more elegant and flexible.
For example: 'settings', 'mobile' and 'web', rather than 'web settings', 'mobile settings', other kinds of tags for parts of web and mobile (ugly and hard to manage).
However, this only works when tags in filters are combined with AND. Otherwise using multiple tags in filters combined with OR, as at present, simply results in a large results set with no precision.
Anyone with a large, complex set of features in Aha would greatly benefit from having the choice to specify filters with AND instead of OR, to support the use of precise, elegant tagging; especially when preparing reports in (for example) web pages.