Well, at least I would never change the play style I like to a (for me totally boring) play style just because my play style lost XP rewards. Would you? I'm sure not. So why expect it from thousands of other players around?B is viable if killing zombies has a point. Ether a chance of good loot, experience or clues. As the game provides no real benefit to killing zombies, the intelligent, non-cheating person makes their base below ground.
The non-cheating intelligent person you are imagining would turn off zombies completely as that is a valid option and it allows you to sit there and just watch the time go by. Then stop playing because the game has lost any use except for building and in that regard minecraft is probably the better alternative. Or mine sand in the desert with an auger, because mining in general gives too much xp in A17 compared to other methods.
Giving xp for kills is a standard practice in the gaming industry, it is working well enough in many games and perfectly in some. Many players are so used to it that they can't imagine playing without. But it is also one way to train players to expect micro achievements every few seconds and to train player to play the meta-game instead of the game.
And that is my main reservation. In a survival game zombies should be killed for self preservation not for farming xp or as micro achievements in the meta-game of getting to the next level.