Why is the Pointcloud2 message large compared to raw sensor data?

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According to section 8.2.1 of the [VLP-32 manual] (https://icave2.cse.buffalo.edu/resour...), the data packet rate in single return mode is determined as follows:

There are 12 firing cycles in a data packet. 
12 x 55.296 μs = 0.663552 ms is the accumulation delay per packet.
1 packet/0.663552 ms = 1507 packets/second 
1248 bytes/packet* 1507 packets/second = 1880736 bytes/second
-> 1.9MB/s

However, by inspection of the PointCloud2 message with rostopic echo, we see that each point is stored as a 32 byte value, which means that the data packet rate is increased by a factor of 10:

578688 pt/sec x 32 bytes = 18518016 bytes/second 
-> 18.5MB/s

(Points per second value taken from section 8.2.4.1 of the VLP-32C manual)

Assuming that my reasoning and calculations above are correct, I have the following two questions:

• Can anyone explain why ROS stores LiDAR point data in such a large data type?
• Is there any way of reducing this size down to something closer to the raw data output from the sensor?