If the description of the skill and its trait specifies a radius, then 30 meters is a huge zone (War-chant radius with the talent is 20 meters) which is unlikely to have the problems you described, rather the opposite, it will be difficult to use such a skill because of the effects of control. If it's a diameter, it's still a pretty wide area, and given the not too long recovery time of the skill it can always be used quickly in a new position. The game is full of positional skills like banner and tar, and they don't cause much of a problem for gameplay.