Hi. This is not our new Toyota, but this Prime Advanced is our first "modern" Toyota and our first hybrid. We just noticed that the car requires us to "hold" the shifter in "neutral" position for a bout 1-2 seconds (approx) for it to engage in neutral. Shifting to others does not appear to require this extra "hold." Is there a good engineering/safety reason for this feature?
No. Why would you ever want to be in N? Toyota is required by law in the US to offer N, but it almost never is what you want. (I can think of two reasons, you want to test your friction brakes, and you are suffering from the mythical unintended acceleration)
I suspect it's because the shifter springs back through N after you select R or D, and thus the requirement to hold it in N to actually select N. If the shifter actually stayed in the position of the selected "gear", you wouldn't need to hold to get into N, and you could tell what "gear" you were in by position of the shifter, just like the old days of about 10 years ago. These newfangled shifters are HORRIBLE, and have KILLED people including the actor who plays Chekov in the new Star Trek movies: When Bad UI Design Kills: Is Poor Shift Lever Design to Blame for Death of Star Trek Actor? - Core77 As for the usefulness of N itself, I find it absolutely vital. For example, if you break down and the car is being hoisted onto a flatbed tow truck, the car will be put into N. Also, after driving the car up on ramps to do an oil change, I use N to allow the car to settle naturally into position at the top of the ramps, and make sure it's not trying to roll back down the ramps. (just make sure to put it back in P and chock the wheels before climbing under!) Both of these uses involve top speeds well under 1 mph.
Accidentally shifting to neutral with the old mechanical shifters was a common problem rarely talked about. I remember that happening with the old 90's Corolla from time to time. Just bumping the shifter reaching for something was enough to nudge it out of drive.
Jimbo has it right........except for the first word. YES there is a good reason for having it that way. You should NOT use N in any kind of "normal" daily driving conditions.
Another good time to use N (but probably not relevant to a Prius): Sometimes when trying to stop on ice, the un-driven wheels will lock up while the engine is still driving the driven wheels, especially when the engine is idling fast during warmup. Not so much a problem with ABS and traction control, but scary as hell with rear wheel drive when the front tires lock up and the rear tires are still pushing. Pop the transmission into N and now all wheels are helping to stop. None of these count a "normal" driving situations, but you can have my N position when you pry it out of my cold, dead hands
Neutral is easier to coast then lightly pressing on the accelerator and holding it in just the right place for zero torque. I have a couple of places where the slope is exactly right to coast for an extended period so I use neutral in those locations.
The reason is for safety. The shifter is an electronic switch. Without the hold, a slight bump could knock the car into neutral when not desired. My wife still managed to do it do me on the highway with the hold in our gen2. Some automatics have the D to N shift gated to prevent this also.
I like Neutral for times when I'm parking on a steep hill, and want to angle the front wheels and roll a tire into firm contact with the curb. Doing This in Drive or Reverse just messes things up. I'd agree the electronic, return-to-centre shifter is the reason for the delay, and further: that it's a solution in search of a problem. And actually creating its share.
In many winter climates, that very much does count as a 'normal' condition. But as you said, this doesn't apply to a Prius. It applies to old technology non-hybrid automatic transmissions lacking ABS / TC / VSC / EBD. With all these new TLA technology additions, it should now be a non-issue in most modern cars.
Back to the original question. As others have touched upon, you go through neutral on the way to drive and reverse and the shift lever returns through neutral when you let go. If it didn't need that pause, you'd never get anywhere; it would be stuck in neutral or park. And there may be some desire on the engineers to force you to be sure you really want neutral and aren't just shifting in a lazy way. I've hit many a false neutral that way on the motorcycle.
All you need is a lock button to keep the shifter in place. Not an entirely new shifter that always pops back to center like the prius. It's just one of those annoying things car manufacturers do to make the car seem sexy -- when in reality it was better before.
The traditional shifter is a hold over from when there was a mechanical connection between it and the transmission. With electronic transmissions they aren't needed, and making them look and feel like how people's parent's and grandparent's shifters work takes up space and adds weight. Pull one apart and you'll likely find that the shift lever is flipping electric switches as you move it back and for.