Wow, I could not disagree more.
With NMEA0183, you need to solder, crimp, twist, or make the electrical connection some other way. You need to figure out which device is the sender and which is the receiver. If you want to connect multiple devices, or send the same data to more than one device (like having speed displayed at the helm and down below) you need yet more things.
With NMEA2000, when you want to connect two devices, you just connect them with twist lock connectors. There is no soldering, crimping, or other things that can go bad. If you add another device later, you just install a T connector and you're done. It doesn't get easier than that.
I think you are mixing up specific details of physical interface and protocol implementation. There is nothing that prevents equipment manufacturers from providing a uniform serial connector - but generally speaking this was not done for historical reasons.
The ethernet cable requires connectors simply because ethernet signal will be lost using the kind of connections that are often result from manually made "crimps, solders" etc. Just that fact alone should tell you something about resilience of protocols in face of real world conditions.
The same goes for adding devices. While the ethernet connection is deceptively simple in appearance, there is far more going on under the hood. Essentially your devices must act as network bridges to move traffic around.
I am sure that both the sales methods of manufacturers and the "packaging" they use make NMEA2000 appear "easy" and more user friendly, but as a technology it simply isn't so.