If I pay $1000 for a phone, I shouldn't have to worry about...
A lot can reasonably follow this like "it breaking when I drop it". I'm over asphalt and concrete far more often than water.
But we want thin phones with edge to edge glass, good speakers/mics, headphone jacks, SD card slots, even removable battery and high degree of reparability, etc.
That makes it tough to drop/water proof them. I know some OEMs try using various methods, but if their success at this is what they would have us believe, they'd be guaranteed (which they are not).
So should all phones be drop and water proof? In an ideal world yes, but we don't live there, and there are real design compromises that must be made to implement this that not all of us are willing to accept, especially if there are no guarantees.
Fortunately, if you really need this kind of optimization, there are phones that provide it. Unfortunately, none of them have an unadulterated instance of Android.