How can I include categories in version 3.5.3 of numbers?

They did. See here for some workarounds with suggestions by Yellow Box, t Quinn, and others.

How do I create a "pivot table" in numbers 3.5?

Return List of Unique Values and Count Occurrence

And contact Apple for your Product feedback

http://www.apple.com/feedback/numbers.html

For a formula-based "pivot-table like" workaround try SUMIFS and COUNTIFS something like this:

Or for a quick "Category type" analysis without using formulas, try this Sum by Category Automator Service (Dropbox download).

To install simply double-click the downloaded .workflow package and, if necessary, click 'Open Anyway' in System Preferences > Security & Privacy.

To use:

1. Select the cells with the data you want to analyze (exclude header and footer rows).
2. Answer the prompts asking you to designate the 'Categorize by' and 'Sum by' columns.
3. Select 'Sum by Category' from your Numbers > Services Menu.
4. Click once in a destination cell (typically in a separate table).
5. Type command-v to paste.

SG