Bob, on the subject of calling forward pax to the gate early, I am afraid this is due to the pressure that the airlines place on handling agents to achive "on time departures", and as you state "it took 30 mins to board a 735", this last statement sums up the reasoning behind servisair and other GHA's calling pax forward early as boarding the aircraft via an airbridge can take a long time, especially as more often that not the cabin crew are content to let pax block the aisle while the take time to put various items in the overhead lockers and then remember that their daily newspaper is up there !!
So please have a little patience with the handling agents and just take the time to watch the boarding routine in the aircraft aisle next time.
