Hi Skyeword,
Rotating text is available for labels on the horizontal axis of charts, but, as you have mentioned, is not a supported feature in spreadsheet tables or elsewhere.
Regarding Export to Excel—That's always an option, and if you need features supported by Excel and not supported in Numbers, the advice here in Apple Support communities has generally been 'use the tool best fitted for the job.'
As well as Excel, you might check out LibreOffice, an open source and free to download and use application that more closely matches the Excel feature set, and is one of te better documented applications of its type.
And regarding "iWork is not available as a category, only Apple Works... Curiouser..." There is an iWork community here—iWork for iOS. The iWork applications, Pages, Numbers and Keynote were marketed as "iWork" only from late 2007 until about 2012. The Mac versions have been available as individual applications since the first versions after iWork '09. And the iOS versions were always individual apps, with the only iWork reference being the iWork for iOS community here.
As for the AppleWorks community, it's main use recently has been as an address to which new users send question for which they don't know (or can't determine) the best place to send those questions. Fortunately for those users, there still several subscribers to the AppleWorks community who'll redirect their questions to more appropriate forums.
Getting back to text rotation—The participants in these user-to-user communities can offer you workarounds using the software as it currently exists, but have no control over changes to the software necessary to add the features that require those changes. For that, you'll need to speak directly to Apple, using the Provide Numbers Feedback menu item in the Numbers menu.
Click on the menu choice, then make a Feature Enhancement request.
Regards,
Barry