I'm currently working on a Drupal build where I'd like users to be able to easily add icons to menu items through the UI. Enter FontAwesome, the scalable vector icon font that leverages the power of CSS. That in combo with the infamous Menu Attributes module allows users to add custom classes to Drupal menu items via the Menu edit interface on a per menu item basis. This is ideal for what we need to accomplish.
A typical use case for Entity Reference and one that I'll use as an example is if you have news stories on your site and you want your editors to be able to pick a specific related blog post and show it on a news story node.
Drupal 7 has an option to turn on a default View for Taxonomy term pages via the contrib module, Views. This is generally pretty good but if you want highly designed pages with additional custom fields than what the default view renders, you could simply update and customize this view but there's a few drawbacks.