I could think of a few reasons why Internet connection could be helpful in this case...for example:
Gathering information about how many times dishwasher is being used could lead to overview of how much water/ energy you are using over period of time. Eventually it could advice user on much he/she could save if the machine was used more efficiently (for example, fill it better before use...). It could advice you on usage of different programs, with aim to improve efficiency/ cost savings/ environment, components wear out, provide for maintenance advice etc.
Most of the people push the button ("highest cleaning settings") and forget about it. If the machine is broken, they simply replace it with new one and don't give it another thought (apart from complaining that everything used to be better "in the past").
Especially from the perspective of protecting the environment, this could prove positive (e.g. if dishwasher is properly maintained, the equipment lifetime could maybe double). Water could be saved by more efficient usage, etc.
I agree though that companies should think first, engineer and design responsibly (and demonstrate the added value); rather than adding features "without thinking"....(especially if they obviously lack appropriate ICT competence).
Though what is happening at the moment is that people buy an "intelligent device" because it is "cool" and have no idea why (and most of the time the functionality is half-baked and not working properly so they do not use it anyways). As well as the manufacturers don't care because if it works and if it works works well, they will end up selling less dishwashers in first place, or be "forced" to work on more environment friendly (read: more expensive) models.
Idea is thus good. Execution...not so much (across the board with the IoT devices for now).