Yeah, I guess that's the reason, and if pushed on the issue the club will probably chunter on about obscure kit rules, exposure, shirt limits, sponsorship rights, marketing agreements etc. They would also probably say that if they didn't wear the green shirt at every televised opportunity then no one would buy them, but does anyone really go, "Wow! I didn't know Brighton played away in green! I must get one!" After all people buy the training tops and we never see them.It's all about the marketing.
Live on Telly, too good a chance to miss.
....
EDIT: I must say that actually I like the green shirt as an item of clothing. However I never buy replica shirts so all the exposure in the world won't get me to buy one. And if you're the type to buy shirts you'll probably buy it anyway even if the team never actually wear it. Gotta get them all.