I don't think it is shoehorning or removing choice, but there has to be some synergy to the issues being faced. Leaving it totally up to the player to either kill all mages, kill all templars, mage independence, etc etc is too big a gap for continuity. The only way it would work is if we didn't play in Chantry controlled lands again for several games and then when we came back, the loose ends had been tied up off screen, which effectively would make your choices meaningless anyway. Its like in DAO, there were restrictions- We had to have a king for Orzammar, we had to pick someone to rule, we had to stop the blight and save Ferelden. The idea that we will be able to make such massive world scale changes that can be so dramatically different from one play through to the other would only be feasible in a stand alone game, or the final installment in a series. What you are asking for Pro Templar- Pro Chantry- Pro Mage endings is the equivalent of asking DAO to have allowed for you to either stopped the blight at Ostagar saving Cailan and Duncan, stopped it at Denerim like you did, or joined the blight and conquered all of Southern Thedas under the horde and now you have to incorporate all three of those endings into DAI.
I think so too. The Warden and Hawke did many good and/or important things during the game. However, despite many players' wishes, those aren't the relationships with the companions, who they chose as ruler in whatever kingdom, or which side they supported.
No, the important things are already scripted:
-The Warden defeated the Blight in record time.
-The Warden put an end to the Fereldan Civil War.
-The Warden put an end to the succession crisis in Orzammar.
-The Warden saved the land of Amaranthine from intelligent darkspawn.
-Hawke became an influential noble in Kirkwall.
-Hawke stopped the Arishok's attack on Kirkwall.
-Hawke was pivotal in the Mage-Templar crisis in Kirkwall.
That's what people in Thedas will remember about our heroes. But none of them represent a deep, permanent change in the global status quo. None. The same way, I can see the Inquisitor being remembered for refounding the Inquisition, putting an end to the Mage-Templar War, putting an end to the Orlesian Civil War and solving the Breach crisis.
So far, no one has promised that we will change any other things than our own Inquisition.