Why are you so eager to jump on people just because they choose to post their opinions? Its a forum, that's why everyone is here.
there is just to much UNINFORMED opinions running around here really. but opinions none the less.
The Dragons aren't Stationary, and you can Happen upon one or it upon you at almost any given time into the story, from what i've read its not scripted or rather static. so different dragons would show up in different area's as well as being able to ravage towns.
as it looks, by no means will Dragons be the chore that was Oblivion gates thats for sure, you -have- to take them down or risk some consequence it seems.