I think that the problem with boarding passes that have no times is uncertainty. The problem is that DHS is a small park with not as many attractions or high capacity rides, so you are left to wait for hours on end (not knowing until when you will be able to ride ROTR), also waiting in very long lines for Toy Story Land or the other E tickets and then being left with nothing to do or the ability to park hop because you don't know if your boarding group will be called, adding to the fact that park hopping can take to up an hour. So you might have hours with nothing to do, or to wait two hours yet again to ride something else. I think it's just bad management not to handle it like fastpasses (Disneyland style) where you get your "come back" time and then you decide if you park hop or you brave the lines of the other low capacity E-Ticket rides.
Disneyland can get very crowded and get long wait times for E Tickets, but you don't get as frustrated because the more egalitarian fastpasses make up for it. Yes, you might wait an hour or an hour and a half for Indy, but you got your Space Mountain fastpass or viceversa. Even in a crowded day you can ride 4 to 5 rides with fastpass. There has to be a better way for DHS