Thin clients suck because they don't make enough money for Microsoft
Well implemented Java (or other) based interfaces can run on low powered machines with most of the interface being created dynamically on the client and compact messaging between client and server, reducing bandwidth and speeding up the net. Include a distributed (even globally) server side and you have a fast and affordable internet for everyone. Only trouble is it doesn't turn as much profit. Why buy a new P4 when the old 486DX will do? Because the 486 won't run your new bloatware from Microsoft.
Why get the latest bloat-ware? Because it's the latest so it must be better.
To give a concrete example of why a fat client is bad for the net ....
The string "Hello World." contains 12 bytes which an applet could make look very pretty.
Put it in HTML, say white Arial/Helvetica bold italic on a black background in a table with a title, and it comes to about 216 bytes.
The same string saved as a Word document with no formatting whatsoever turns out to be 19,456 bytes here ... what do you get?
And if that's not bad enough, have a look at the html code that Microsoft products generate. Yes folks, thin clients suck becuase the makers of our most popular software and hardware want us to upgrade every year and thin clients would by their nature be built on open platforms that maintain backwards compatability.
Point of note: Star Office on my AMD K6 166 Mhz Linux box at home runs faster than MS Office on my Windows 2000 PIII 566Mhz at work. hmmmmmmmmm...