Still incompatible with other clients.
Taking your example, all other clients would fall to their default colors.
examples: *and lets say you have it set up to use green as the default text color*
mIRC v6.2 (maybe?)
AutoGreeting: [color:blue]Welcome [color:red]LeDork to #Stupid[/color][/color]
Previous versions (or other clients):
AutoGreeting: Welcome LeDork to #Stupid
I guess a good compromise would be to design/setup a new standard, have it recognized for a few months to a year (ie, v6.2 would work properly with it) but not have it actively available for people to easily use (until say, v9.0 (okokok 6.3)), so that other clients have a chance to implement the updates and older clients might have someone develop a plugin to have it work properly.
This would also allow for a certain amount of backwards compatibility.
