honestly the only time I thought it should have seriously changed is after the Qunari attack, The whole area is blocked off and is never used, It would either have turned into a slum or Storage area for one of the warehouses or shipping companies. But I guess without a Vicount, reperposing an area can be a serious issue.
Why does it span so long its to tell a story, cause if after he goes to the deeproads he is suddenly the champion then the story doesn't make sense. The story isn't also just about Hawke its about Meradith as well, going from Knight-commander, to psychopath red-lyrim maniac.
You can't do that within 1 year of time without everyone going... yea right whatever... its called 'Suspension of disbelief'. Having to much go on in one year makes it hard to believe, having the red-lyrim eat away at Meradith's sanity over the course of years expecly after Bartrends episode. Increases the believability of Meradith going crazy later on in the story.
Also the time also shows the events leading up the the Qunari attack, considering how irritated the leader gets over time. So IMO the time element was used pretty well.
Sure sure, the world didn't change that much, but look at any "Town" even today, you will notice that it wont really have changed that much over the course of 10 years. Sure paints would have faded alittle things may be abit more rusty or dusty. But all in all not much would have changed, And if a city is decently upkeeped with enough work you wont notice much of a change.