Once bug 105933 is solved we should also provide means to share fancy table styles via extensions.
Moving to NEW
Why table styles should use a different sharing workflow than other kinds of styles (e.g. paragraph, character etc.)? Styles are usually shared via templates, not via extensions.
Table Style is not a real style neither used similar to document styles. It's more like artwork like smartart, gallery content etc.
The use case of TS extension is to create a company branded TS and install it on all systems to be used in all documents. Per extension you can also share the TS with the whole community.
Doing it via template might be possible be feels wrong to me.