How else do you want samsung to differentiate a plus model? To charge an extra 100 dollars for?
Bigger screen
Bigger battery
2gb more ram
Dual camera
Etc.
It's a 3 tier option
S9
S9+
Note 9
How else do I want them to do it?
Well seeing as I have more of a preference for smaller phones these days, I find the likes of Samsung's S8/9 Plus and iPhones Plus models too big for my tastes.
So do you think that me, as a tech enthusiast who wants a phone with a fantastic camera should have to either just deal with the fact that choosing the smaller model won't provide as good an experience, or fork out more for a phone that is unsuitable due to how big it is just to get a feature that really should be available for both?
This '3 tier option' you quote is not the way it should be. Either make a smaller phone that is one on its own (like an SE) or keep your flagship devices the same apart from the obvious bigger screen / battery. Speaking as a consumer, those should be the only differences and customers should not be discriminated against for choosing the smaller device.