You know the answer. It is #1.
Someone once said to me many years ago that, (assuming you are on one of the better PWHL teams with excellent coaching), you will never have better coaching if you get to D1 than you had in the PWHL.
I was astonished. It just couldn't be true, could it? Those are big money coaches. But I heard it over and over again from players on different teams. Many of these played on teams that have been ranked in the Top 10 in the country at D1. Having watched lots of D1 hockey over the last 4 years, I know that to be very true.
So part of the answer is that most of the coaches at D1 are not actually all that great, and don't seem to understand what they are missing. They may be good recruiters, and/or good strictly at the x's and o's, are staunch disciplinarians, or great administrators and politicians, but most are NOT great leaders and motivators, nor are they exceptionally smart about the role of creativity, fostering great chemistry, nor the need to make in-game adjustments.
Many of these coaches are quite obsessed with speed, and the game is definitely faster at D1, although some quite good teams have never been especially fast. You would think that hockey sense is also more prevalent at D1 than in the PWHL, but the fact is that it is actually comparatively low to what you might expect (see obsession #1). That especially surprised me.
So I've noticed over the years that it's really not all that unusual to find "important players", and skilled players blessed with great hockey sense but average speed--who performed very well before D1, to spend much of their time on the bench while their previously proven talent is wasted....while some of those speedsters who tend to stickhandle their way by themselves into the corner and accomplish little, get their ice time.
And they wonder why their teams don't score more, or win more than in previous seasons, or their players don't produce to expectation. It must simply be because they don't have the Agostas/Johnstons/Poulins et al. Riiiiight. Good excuse.