If I skip this service on my cruise what will I be missing out on?
The level of service is one of the things that attracts people to cruise lines.
clean bathroom, fill shower soap, new bars of hand soap, replace toilet paper rolls, clean sheets, make the bed, take out the trash (there is no place to dump trash yourself and it is separated by the cabin steward), new clean towels, vacuum, dust, outside cabin clean the glass, any notices or paperwork will be kind of attached to your door if not placed in your cabin. Better to have this done each day. If you call the steward's number you may get a delivery when you are in your cabin or maybe when you are away from the cabin. How are you going to do all this yourself without calling the cabin steward?
Cabin stewards are tested frequently. I would not worry about them entering your cabin.