The cabin steward is just as important to me as the waitstaff. If I have my cabin serviced twice a day, clean towels as needed, the needed information placed in my cabin and the ice replenished I am happy and I find that an acceptable level of service.
If I ask for something out of the ordinary such as: "Putting a lounge chair on a regular balcony" or keeping the door to the cabinet door open for the fridge and the steward complied then I may tip extra.
In the dining room I expect the waitstaff to take my order and do so without errors, professionally and expeditiously. I also expect a somewhat positive attitude but I don't want Mr/Ms. Smiley. I do like to have some chit-chat with the waitstaff but I don't want or expect them to read my mind or become my best friend for the week.
If they do anticipate my needs and do learn my likes and dislikes then I may give them additional.
There have been cruises where I have tipped additional but there have been just as many that I have given no more than the standard gratuity.
I do agree that too many people tip additional to the staff for doing no more than what they are supposed to do. Many people do so because they know how hard they work (but that is their job) and others do so to make themselves feel important.
There is no need to tip additional. Additional tips are for additional effort.