Why is Canon making x0D so quickly obsolet?

Is that going to be every one year? Is Canon considering our money investment or is it not a concern? I think it is quite disappointing to see my 40D losing price (new) after just one year - it is becoming to demonstrate that Canon's approach to update cameras does not consider consumer's sake.

Why they do not launch a new model with all improvements every two years (or so), and stop stepping half improved model every one year (what it seams to me is happening - and I don´t beleave it is a wise approach since people may consider a more stable brand that seams to respect better their consumers launching up-grades - and there are several).

B. regards.