It would be interesting to know why.  OTOH, there may be a market for 
add-in functionality for applications that are of smaller scale and 
tend to run locally.  It may be that as we learned from HTML, trying 
to solve the ultimate problems before going to market is a way of 
staying poor.  
In the web business, and on every list I've participated 
in, it is always difficult to get folks to consider alternative 
markets for tools and content.  For example, in VRML, there is 
an almost maniacal emphasis on the web while ignoring the CD 
market where the problems of "heavy" datatypes are evident.  
For example, any animation profits by *good sound* as can be 
provided in a wav file, the human voice, etc.  It is only 
recently that some are waking up to the potential of marrying 
rock or pop albums to innovative 3D.  Because of the need to 
rehost the art into new media every so often, there are lifecycle 
problems which open content standards help to solve just as 
markup technologies helped to solve these problems for 
long lifecycle document collections.  
Thar is life in them thar niches. :-)
len