Being able to keep your keys in your pocket/purse/etc when entering and driving a car I find to be a pretty big upside. Especially in areas where it can be cold enough to freeze the key mechanism on your car door.
The other thing -- do the key fobs have an on/off switch? If not, you wouldn't be able to have a spare "hidden" under your car somewhere (yes this is insecure anyway, but it works for most people).
Pop out the battery. You don't need the battery to use the hidden spare if you lose your key: there's a physical key hidden inside the fob to unlock the door, then a slot on the dash to stick the whole fob into to start the car. It's there so you can't be stuck unable to start your car when the fob's battery dies.
Also, the dashboard will always tell you if you are inside the car but key is not detected. So even if it miscalculates where the fob is and let you start the engine, that key-not-present light will be on as you drive off.
I think the trade off makes it not worthwhile. If it's optional, I prefer a normal key.
OTOH, There are lots of other cool gadgets that I'd like to see. A car that remembers everyone's seat position and mirrors, that's progress. Manual transmission, normal key, smart seat. That's my niche.
The simple solution: Just go back to pressing a button to unlock and putting the key in the ignition.
If the manufacturer really wants to keep the feature, then they could switch to those keys that flip out like Fiat has and just turn off the near-unlock functionality on the remote when the key is folded in.