I have to agree with Aiken here. Your idea would need to be geared to the uneducated more than the true hobbyist. I worked in many retail pet stores in the U.S. starting back in the 1970s and have seen periods where the hobbyists waned but the desire for fish tanks for furniture increased. The hobby changed from a kid's hobby to an adult's hobby because that was where the money was. Your idea for simplicity would have worked better during that period but home tank maintenance companies filled that void because those people weren't interested in being a fish hobbyist, they just wanted something alive and different from their neighbors. Even that period waned as people got tired of having to actually pay attention to what was happening in the tank in between the times the the service company was going to the home.
There are two types of fish hobbyists: Those who just want to have fish and those who want to learn about the fish. You learn more in the doing, not in the having done for you. Using your own experience with the shrimp, didn't you learn more by needing to find the appropriate medications, suppliers, species than if someone just said " Here, do this and this and that and you'll be okay."? As Aiken stated, a successful tank will have a group of compatible fish species. Because of this, there is no " one size fits all" to fish keeping. Different species need different foods or different temperatures or different forms of decorations, etc. This means that to sell an uneducated person " The answer to fish keeping", to be responsible, it should really not stop at the setup but at the fish source.
On a personal note, my introduction to fish keeping as an inquisitive 6 year old led to a 45+ year career in the tropical fish industry. While my story is unusual, it's not unique. I've been everything from a commercial fish breeder to a wholesaler, importer/exporter, retailer, fish collector, system designer and most of all, an avid hobbyist. I had a certified Ichthyologist as a mentor and he explained to me what was happening within the system. It was from him making do things that I learned how to do them under different systems.
Hopefully this just gives you some more food for thought.
For the saltwater trade, a " done for you" type system can be beneficial for those who are keeping more delicate corals or other more delicate species but for those just keeping fish, I assume the cost of your setup wouldn't really be a financial benefit. That part of the hobby is expensive enough as it is and most of the filtering parts can be DIYed. I was in Brazil at a restaurant that had a 40' long aquarium in the waiting area. My party got a "behind the scenes" tour because the owner was a client of our customer. The tank was run by a computer system as big as a home closet. Here's the catch, even with the computer running everything, the corals in the tank were not doing well. That was part of why my buddy and I were sent to Brazil. To figure out why they weren't. The lighting was wrong, the placement of the corals was wrong, the circulation within the tank was wrong and all those things combined were the problem. So you see, without being involved in the care of the tank, a lot can be missed. It's more than just the system. I can see your system being better for commercial places like this restaurant or say, Dr's offices, business waiting rooms, etc as long as it's connected to a maintenance service if the people don't have the want to do it themselves.
As I said, I've seen a lot of " next best things" in my 60 years in the tropical fish hobby and most of them no longer exist because they just weren't necessary for the hobbyist. I think your analysis here " a smart fish tank follows "the trend" of a smart house but it is not necessary for the hobbyists as much as a new car with sensors and warnings is not necessary when given to an expert driver." is spot on, even for the average hobbyist.
Hope this helps.