The slits on the side and the bigger holes on the top suggest the enclosure is fairly thick. I don't think one would need to worry about the enclosure not being strong enough. I suspect one can stand on it without making a dent.
If it is a message what would be the start point and direction to read. are small holes a 0 and bigger ones a 1.
Or are 'missing' holes a 0, small holes a 1 and the bigger ones a 2. In this case it isn't binary anymore and would make sense if there were 3 hole sizes. We could be having nibbles instead of bits making the encoding more difficult and increases the amount of possible information.
It looks like they wanted holes on top (which would only do something when the bottom and PCB also had holes or there would be openings on the side or rear. Maybe someone came up with not making slits (so 80's) or holes of equal size in a boring pattern and decided to make it more fun and aesthetically pleasing ?
Nah... the message thing is more appealing. Maybe someone figures out the message... some hints
@JohnYang1997 ?