(Ulrich Fuchs mail@ulrich-fuchs.de):
Yeah, that nested table is a nuisance. I'll have to think about that.
Its not a nuisance, it's an advanced feature of HTML
WIKIPEDIA IS NOT HTML. Wikipedia is a collection of free encyclopedic content, currently being delivered to users by the technology available to us at the time, which happens to be HTML. Wikipedia's content should be described in unambiguous ways that preserve the content and structure of documents, and that can be rendered readably and edited easily. HTML fails to meet at least some of those criteria (notably ease of editing).
A Table - and especially a table with complex structure, nesting etc - *IS* a complex thing. You will not be able to eliminate that complexity. As soon as you are trying to do it, you will greatly reduce the flexibility. As soon as you add that flexibility again, you add the complexity again. So why re-invent the wheel by having (in the end) the same problems in just another markup language?
Believe me, I won't let that happen. I have no interest in translating the complexity into a different language just for the hell of it either. If I can't make it simpler, I won't change it.
Yes, I think we might have to give up some "flexibility", if it's only the flexibility to do things that don't really improve the user experience. Tables in general are important: they organize information neatly and ease comparisons of similar things. But I'm not at all convinced that nested tables are of any use other than to show off coding skills.
I strongly support the table:namespace concept: It offers all the the HTML flexibility you need, and you keep the article source clean of the table code.
The contents of the table IS IN THE ARTICLE, whether you hide it off in another page or not. The tables are part of Wikipedia's content, and if they aren't easily editable, they aren't useful.
That said, I'm still open to the idea of transclusion in general: that is, having pages whose whole contents are included into a referencing page. That would allow us not only to separate things like tables, but also things like boilerplate text. A syntax like [[include:xxx]] could be used. That would also get us nested tables (and it might also be a performance nightmare!)
If we can have the table syntax proposed additionally, thats just fine: A newbie will start with a simple table, as soon as it gets more complex, an experienced user can move it into a full-fetaured html-table in the new namespace and link it from the article.
I don't like that idea much either.