I've played plenty of offline, been doin since NHL 96 - That said, yes if it weren't for trophies I wouldn't play those modes at all (I stopped after 500 points because breaking Gretzkys record would be boring).
You're playing against bots - there was never a tangible reward outside of regular completion satisfaction, which you still get. Most players are impatient and would like to jump through as few hoops as possible.
Difficulty can always be adjusted via sliders so juniors is just fluff until you reach the true goal - NHL; the way I see it, they're just speeding up the process. I completely understand your argument as a simulation player, but the game as a whole has obviously started to shift towards a more arcadey feel for mass appeal.
I hope for the hardcore simmer's sake they can get to a point to add absolutely everything to create a 100% authentic experience, but there are other modes that need attention too.
Is story mode bare bones? Sure, but its more than we had previously; a good first step on the road to something truly great.
All the dialogue options, all the animations, art, screens etc. was energy taken from other areas like the EASHL that I care about so we just gotta roll with the punches.
In real life, yes, juniors is obviously important, but from a game standpoint I personally just think it's just filler, fluff to pad game time with - Franchise, BaP, GM mode... people even want referee modes, its basically all the same.
I'd like everything to eventually blend together so there can actually be a reason to participate in it all - finishing juniors, winning awards etc can all give added boosts and accolades to your players in online modes.