The advantages of waterproof molded ear plugs are many. If you are only an occasional ear plug user then you might get away with a pair of foam ear plugs for sleeping and noise. Molded ear plugs are far more comfortable and more effective in many ways. Wearing foam ear plugs often or for a long time can lead to sore ears. There are many occasions when molded ear plugs are superior.
Waterproof molded ear plugs are much better for use in water than other types. They last much longer and so are better value for money. Some varieties such as ZenPlugs also contain an antibacterial compound. This helps stop ear infections and the dreaded swimmer's ear. Molded ear plugs stay in much better than other types. This makes them great for activities such as surfing and waterskiing when people are moving around a lot. Because they are waterproof they are wipe-clean and last much longer. They don't become clogged with dirt and ear wax like other types.
Molded ear plugs are more comfortable and effective than other types so you are less likely to be woken at night. Foam and wax types often stand proud of the ear and so press in when lying on your side. Foam also expands so pushes itself out of the ears. This expansion also leads to pressure in the ear. People are more likely to pull them put in their sleep.
Summary; waterproof molded ear plugs have many advantages over other types. They are great general-purpose plugs which can be used for sleeping and watersports.