Yes it would be great if transinclusion was possible. The user case is like I was describing in the first thread. Using the tag function wiki variables can be used with html, which opens up the possibility of templates where the user could set the variable, but not be able to add raw html themselves. In my case I operate a wiki that has the yellow pages data of the United States and by allowing the end users to set the variables I could add html to let them embed their Instragram, Pinterest, etc., per listing. Additionally I could pre-design forms in html, like a Contact page, Employment Application, etc., where the person editing the page could actually change the questions (have the questions set as wiki variable) and then present to the end reading user a form to fill out (kinda of like a form designing system seen on sites like Wufoo).
So, not to get long winded, transinclusion would be awesome, great and most, most helpful.
I'll try the settings you suggested and see if it solves the problem of only operating in One Naemspace. I thought I did have my code the way you show, but maybe I make a small syntax error. All the best and thanks again for the work.