Spoilers and pitching moment balance
For most commercial jet configurations inboard spoilers have both a direct impact on wing lift and an indirect impact of tail lift as the flow over the horizontal stabilizer is disturbed. As a result, inboard spoiler deployment tends to generate a net nose up down pitching moment. In contrast, outboard spoiler deployment tends to generate nose up pitching moment. Care is usually taken during design of spoiler deployment for speedbraking (particularly in-air) to balance usage of inboard and outboard spoilers so as to bound the net pitching moment that results.
The A320 guidance to avoid large lateral stick displacements due to the nose up pitching moment that they generate suggests that outboard spoilers are used more for roll control than the inboard spoilers.
Another issue that this points to is the transition from ground to air and the associated roll control law mode change. For heavy crosswind takeoffs does the A320 pilot have to quickly remove lateral stick input necessary on the ground in order to avoid commanding too much roll rate during climbout? How about the similar transition from air to ground with heavy crosswind when the lateral control mode is switching from roll rate to the ground mode?