The Motor Stage is primarily a Haptic affair.
The major task for babies in the Motor Stage is to learn abaut themselves. They need to gain an awareness of the parts of their body--their arms, hands, fingers, legs, lips, jaw etc., etc.
This is originally completely a Haptic matter. As the child moves around reflexively, feedback begins to build a neural map of their body in the brain.
There is, to be sure, stimulation in the other modalities; and we have stressed the importance of providing stimulation to all modalities to facilitate development of the neural infra-structure for each.
But this information is un-integrated. In terms of basic knowledge about the self--the Haptic modality takes the lead.