Some people have been known to remove their rear pillar to make more space and a larger access area. In my opinion, this is not a good idea.

It is argued that the gear will take the place of the pillar. To understand why this can not be effectively true, consider what all the pillar does. Its job is more than retaining the basic shape of the stern. The pillar keeps the hull and deck of the kayak tight and up to a certain point, prevents flexing. A mix of clothing, food, sleeping bag, etc can not offer the same amount of integrity. Why is it important to reduce flex? See for yourself in this simple kayaker-approved scientifically satisfying test:

Grab a bottle of your favorite brew and drink it. The glass bottle will represent a kayak that has no flex. Now, grab an empty plastic soda bottle. This bottle will represent a kayak that flex’s. Wade in to the water and find a wedged shape rock big enough not to easily move…basketball sized or bigger. Find the point of the wedge on the rock (upstream side) and rub the glass bottle over this, back and forth, with enough pressure to just scratch the glass. Notice that the bottle simply slides off the rock. Now, do the same with the empty plastic bottle. Watch carefully and notice that when pressure is applied (analogous to river current), the plastic wants to bend. When this bending happens, the sliding is slowed and with pressure still applied, the bottle’s momentum will eventually stop (we've got a pin now folks. Not good). At this time, the ends of the bottle (kayak) will be subjected to the full force of the currents. And, if those currents are strong enough, the ends will have no place to go except with the flow (if the image hasn't come yet, think "wrap". Think dire). The severity and speed of these events depends on several factors. It should not be assumed however that you'll simply be able to escape the kayak at your convenience.

In summary, the flexier a kayak is, the more likely it will bend when making contact with a solid object. When this happens, the kayak is far more prone to stick to that solid object and if the current is strong enough, wrap itself around.

Furthermore, even if the gear could provide equal amounts of rigidity to the pillar, the kayak is still going to be weaker. Here’s why:

In conjunction with adding rigidity, the pillar also acts as an internal beam of sorts. However, a beam, whether it is in a building or kayak, is only as good as its connection. Enter the modern day kayak seat. All good kayaks today have a place in the seat for the pillar to sit into, or in structural engineering terms, a beam pocket. This acts as the connection. Removing the pillar and putting gear in its place is like cutting the beam in half that holds the roof up on your house, at the connection, and then hoping it doesn’t fall on your head.

While the latter example plays less of a structural role in a kayak than the former, it never the less plays a part in the over all integrity of the boat.

Having a pillar in place does not guarantee your boat to be wrap proof, but removing it does guarantee it will be more susceptible.