Exclusive use by default?

I live in a complex of 16 in Hornsby area and at the front of the building there is a large common area of grass and garden. Whilst this area is clearly defined as common property one unit (lot 1) has much better access to it, their balcony door opens on to it. Other lot owners/tenants have to open a gate and go down 8 steps to gain access to the area.

In the 8 years I have been there as far as I could see no one other than lot 1 has used the area and the old owner had “decorated” the area with a number of pot plants and other garden ornaments. Recently the unit was sold to a new young guy who has made a number of changes to the area – tidying up, new pot plants and the like. I would stress that all that everything he has done so far looks good and is an improvement on what it looked like, but I have two concerns;

1. By allowing an owner to take control of a common area is there any chance he could obtain exclusive use of thearea in the future without OC approval?
2. Should the EC insist that before making any changes to the common area the owner should seek approval from the OC or EC. As I said above so far everything he has done looks good but what if he does something from left field which looks terrible, have we compromised ourselves?