A little more documentation would be helpful (it’s not even mentioned in the reference section Table of Contents).
If I flag a TextAsset as user modifiable … what does that do?
If I change the text property of a TextAsset, under what, if any, conditions does its property change? E.g. can I use TextAssets to save games?
Basically the contents of any text, html or xml file in the project can be accessed via TextAsset. It’s like including a read-only file for whatever reasons you want (mostly because you need large amounts of text data). You can’t change the text of it, and it’s not a separate file that a game could be saved to.
Did you see this page?
No I didn’t see that page, but it doesn’t answer my questions…
On the plus side, my time spent writing text i/o routines has not been wasted 
Also on the plus side (and I guess this is the point), if I want to specify internal game data using text files, I assume it will now get automagically bundled into the final app / plugin file.