See, I kinda see it the opposite way. If I randomly happen upon a rare Pokemon while out walking, nice, but it doesn't feel like I achieved anything. It's no better than having them pop out of an egg. If I see a Pokemon on a tracker and I get to it before the spawn timer ends, then it does feel like an achievement.
A couple of events this weekend that wouldn't have happened without Pokevision (and the like):
1) On Friday, someone in my office noticed Snorlax show up on a tracker. Cue over 20 people leaving the office in the middle of the afternoon to try and get to him before he left.
2) At 1:30am while a bit drunk, I noticed Magmar on Pokevision about 200m away. I ran out of the flat to catch him.
Those events are things that I'll remember for a while, and I have a story behind catching them (or not, in Snorlax's case
). I honestly don't remember where or when I got Clefairy, or Abra for example, two that I found just randomly without looking for them in amongst hundreds of others.