CRM 2013 offers the option to quick-create a new activity via the PLUS-button directly from the main form if the activities grid is placed on the form. But if doing this the recipient is not set though it's clear (at least for a lead or contact). If using the 'old' activities view (navigate via the navigation bar to activities and call 'new ...' the recipient is set. It's the same form but different behaviour - bad for user acceptance.