Yes it IS a toy, but it is not representing a walking robot.
The Macross flies and DOESN'T walk, that is why it doesn't have knees.
Like Hurin mentionned earlier, the part were it can be seen with knees in the movie, is just an animation error.
Of course you are entitled to your own opinion, but souldn't disregard that of others. THAT goes for the both of you.