TotM is too hard. I have a hard enough time understanding positioning with minis. Without them, I would be totally clueless as a player. As a DM, I'm too busy for TotM. Multitasking and remembering is getting harder to do the older I get. I would constantly run into:
Me: "Wait, you said you were moving towards the Bugbear after taking out the Gnoll? I don't remember that."
Player 2: "Yes, he said that."
My daughter: "You're getting old Dad."
Me: "Crap! Ok, now I got to figure out why the Ogre didn't attack you when you were in its way. It actually didn't have the movement to attack the Cleric with you in the way. Screw it. The Ogre attacked the Cleric anyway and you get an OA."
Player 1: "That's the reason I moved towards the Bugbear, to block the Ogre's path as well."
Me: "Ok, fine. The Ogre attacked you instead and used some extra movement afterwards to move around you. What did I roll to hit? It hit the Cleric, did it hit you? Cleric, how much damage did I do? You can put that back on your sheet and we'll move it to the Fighter. Crap. Crap. Crap."


Also, I'm a visual person, not an audio one. Even at work, my coworker has to sometimes show me what he means on the computer instead of telling me. As a player, position information would sometimes make my eyes glaze over and I would rarely have the same interpretation that the DM meant. I can immediately tell prone in the game because the miniature is knocked over and so can every other player at the table. I can immediately tell if movement will cause an OA in the game because the miniature is next to the proposed movement path and so can every other player at the table.
As a player, if I or someone else has to go to the bathroom or head to the kitchen for something in TotM, the DM either has to stop, the person leaving misses information, or has to ask more questions when he gets back. At least with miniatures, that missing information doesn't include positioning.
I suspect that TotM, which we often use for roleplaying (although I do sometimes set up miniatures when meeting with multiple NPCs, just to show how many are there, where they are, etc.; I never know when a PC will Burning Hands them and I don't want to figure out their positioning after the player informs me of this) and exploration, works better for those two pillars. It just doesn't work for me for combat.
PS. This is why we use grids with miniatures as well. We tried using miniatures without grids when LMoP came out and it was a minor disaster at our table trying to figure out who could move where, was someone close enough for OAs, etc. Grids instantly solve those "exact locations" questions for us.