While I understand how PokeVision made it too easy to find Pokemon, a functional tracker IS a needed feature in the game. You cannot say that because the “original” Pokemon games never had a tracker, Pokemon GO shouldn’t either. Why? Because there were designated areas within the games where you were most likely to find generic and specific Pokemon (bushy areas, caves, buildings), and these zones are so prevalent that you can never avoid going through these zones. There is no such designation in real life, aside from finding water Pokemon near bodies of water. In a game, you could spend minutes to hours running around an in-game electric plant in hopes of finding and catching a Pikachu, while in real life, you could spend days to weeks and never once find a Pikachu. Also, while it’s true there are no trackers in real life to tell you where the “animal life” are, they usually make sounds or are distinctly noticeable in real life, whereas Pokemon are fictional characters that are get drawn onto your 5–6" phones.
This is in addition to the fact that the leveling system is completely different in Pokemon GO. There are no wild pokemon, trainers, gyms for your active pokemon to battle to gain exp in hopes of leveling it up/evolving. The only way to do so is to find that same Pokemon many times over and getting candies for them, which means finding and catching Pokemon become even more crucial to progression in the game. Imagine doing this “in the real world” without designated Pokemon zones and a functional tracker. You would be wandering around aimlessly and likely not gain much progress for days on end. I can guarantee that most kids (and their parents) or casual gamers could care less about the grind, and that the fun is catching/leveling Pokemon. You can say I’m not a “hardcore fan” for not dedicating my life to “being the very best” and thinking this way, but when this game becomes a chore to find Pokemon and to level them up, masses of people will get frustrated and stop playing, leaving Niantic and all the “hardcore fans” with a shell of a game that focused on bringing the “true” Pokemon experience when most people enjoy Pokemon merely as a past-time and not as real life. The more people (aka potential spenders) that Niantic loses, the less profitable it would be for them to keep up this game and the servers needed to host, and the sooner the game dies.
Lastly, you say that PokeVision takes away the fun because it’s cheating. While I don’t disagree that the way PokeVision worked made it extremely easy to find the Pokemon you wanted, it provided a service (and more) that Niantic failed to fix (namely, a working tracker). This working tracker got people excited that there were Pokemon nearby that they could use to level up or add to their collection.