Its not a necessity.
You can be a good planner without the architecturally inclined brain.
But drawing skill does help one in making out the plans/maps and understanding them better.
I'm not an architect( though I was trained to be a planner who could draw too) and have many colleagues( Sociologists, Economists) who are not experts in drawing/mapping.
My suggestion to you:
If you are in the learing stage then its better to get acquainted with the process of making maps and using the right color, scale and detail, notations-annotations, orientation and geaography.
And better to have the Maths Background and Science Approach to planning even if you are not an expert in the individual fields atleast try to know the dynamics and the interrelations.
Now does this make you feel better??
You can also ask yourself, "what kind of planner you want to be"? Because there are many kinds and from your intro i can see that you major in Sociology.
OT:
I have been asked to discuss the revamping of the Undergrad Planning Course here as part of a larger team and with the new national policy of opening up the planning course for non science students (right after school), it looks like we need to convince the policy makers that planning does involve statistics, economic( which have maths models), Environmental Science subjects which involve basic understanding of chemical reactions and maths and physics even in transportation planning/engineering.
