I had the same situation when my girl was born, and I did consider putting the cot on the platform area too. The plus side is more floor space, but the concern is whether the cot sits completely stable and level on the platform, because any wobble is a safety risk. I ended up just rearranging the room furniture instead, since I felt better having the cot on flat ground lah. If you do try it, just make sure the platform surface is fully even and the cot legs are secure before baby goes in.