I'd have more sympathy for the "we need a Renaissance and Industrial Age period from Medieval" except for the fact that there's been plenty of cultures which have moved directly from Medieval to Modern Democracies.
Sometimes it works great, other times it doesn't.
However, the idea there's a "proper course" of history doesn't really hold weight with me.
I agree that there is no "proper" course of history. I would like to point out, however, that there is no ideological or philosophical basis whatsoever in Thedas for a widely accepted theory of sapient rights. The only system that comes close is the Chantry, ironically enough - "all are the Maker's children" and all that - but in practice it doesn't go nearly far enough and is not universally accepted anyway.
Without a reason for people to consider others outside their own community to be, well, "people", I don't see how anything even remotely approximating modern Western liberal/social democracy could even be
contemplated. Nobody would go along with it. The identities that matter most to Thedosians are corporate, exclusive identities, not universal ones. I am a mage,
and you are not. I am Dalish,
and you are not. I am a member of House Helmi,
and you are not. I am viddathari in service to the Beresaad,
and you are not.
In order to work, any political system would need to focus more on balancing these communities and their interests against each other, and focus less on compelling them to unify. Which doesn't bring us too terribly far from where we started in the first place.