Eliminate the expectation of a 20% tip and prices will basically go up 20% to cover an increase in base pay for the staff. So consumers probably won't actually save money if tipping were eliminated.
It would also remove a fairly large mental burden on consumers.
This is why I find it odd that people get mad when the occasional customer gives a low or no tip. That's the system, and you're saying you prefer this system because it overall makes you much more money than the alternative, at the cost to consumers and others.
Many of the very best restaurants in the country have fixed gratuity and still have absolutely extraordinary service.
Some how the country hasn't collapsed and all the hotels, restaurants, bars, etc continue to operate just fine and with good service.
The OP would disagree with you.
In the US, it's normal to have a server hovering around your table, and frequently "checking up" on you to see if you need anything. They frequently will interrupt your conversation to ask you if you're OK. Some people would find this annoying, but Americans like the OP love this kind of service.
In Japan, no one is going to come around to your table to see how you're doing, or to take your order. You need to flag them down: raising your hand, pressing a button on the table, yelling "sumimasen!" etc are all pretty normal.
Also, in Japan the service is extremely professional and courteous. The server will not tell you how their day is going or anything else about their life. Americans don't like this: they want the server to act like their best friend and chit-chat with them for several minutes. Japanese servers will never do this: they take your order and then go do other work.
Overall, the amount of service in a typical Japanese is much less than in America. It's one of the reasons it costs less to eat here. Instead of a huge waitstaff standing around ready to attend to customers, there might be just one server in the whole restaurant, and he also mans the cash register, and does various other things while not doing those. That doesn't happen in America. So of course the hourly labor cost to run a restaurant in America is huge with all these people, whereas in Japan you might only need 2-3 people to run the whole place.
Americans like the OP simply won't be happy with the kind of service offered here. It's minimalist and highly efficient, and not at all "warm" or "friendly" like they're used to in America.
(Many restaurants I'm seeing have "18% gratuity automatically added" and yet still have a tip line for those who don't read.)
And remember, you are assuming a zero-net-revenue change.
Maybe your former non-tipping customers would see that 6-7% increase and leave, but your former tipping customers (who may be price sensitive, but tipped because they believe in it) would see a decrease in pricing, from a 20% gratuity reduced to a 6-7% price overhead. And some of them would probably still tip anyway.