How do you go without hierarchical taxonomy filters, when the site heavily relies on content browsing(multiple filters and sorting)?
This is unfortunately a big pain point with Drupal 7.  On my site, I handled this with Views and Panels.

In my case, the hierarchies with places generated by the Location taxonomize module in the form of country / state / city or country / city.

To give you a rough idea of how I approached it: I overrode the taxonomy term path using Panels/Page Manager.  I then added two variants in the following order:


a variant containing a content pane that aggregates countries and shows only those countries with 1 or more entries
a variant containing a content pane that takes a country as an argument/contextual filter and shows users having that taxonomy term as well as  a list of states using the special Panels related terms (show children) block


Depending on the structure of your taxonomy and what you are trying to show, this can be an extremely complicated setup, but it is possible even without direct support from hierarchical select.