I haven't read the original reference for this thread but here is my take.
The RCX hardware seems to be the limiting factor. NQC , Java ... have been developed to provide a textual interface that gives one more programming power. However, the advanced user will want to use a third party interface like the Handy board and now the new Gameboy interface from Charmed Labs. Botball is really getting a lot out of the lego robot kit with the later two hardware interfaces.
http://www.charmedlabs.com
