All of our wildlife and hunting regulations are created, maintained, and updated by the State Legislature.
I'm not trying to be a jerk, but you really seem to be out of touch with the regulations in our state. Spend a few hours reading the current hunting guide books, perusing the DNR website (including wildlife.ut.gov), reading the actual code, and reading the BLM and DWR blogs. You may be surprised at some of what you find (we had a major review and update a year or two ago, and the 2012 hunting changes are substantial).
Not knowing the law, is how people get in trouble for "stupid" mistakes.
Not knowing how the different agencies are working together, is how people start thinking the laws don't apply to the area they're shooting/hunting in.
I'd like to know who sanctions the public land as "Temporary Game Reserves" because DWR do not have the right to do that.
They do have that right, because BLM (and the USFS) grants them that right (and there is a lot of state land inter-mingled with BLM land). BLM (and USFS) and the DWR work together to manage wildlife and habitat. For hunting, BLM (and USFS) allows the DWR to enforce all of the state regulations.
From the first big game season of the year, until the last big game season of the year... nearly the entire state is turned into a "Temporary Game Preserve", and no one is supposed to be shooting, except for hunters. (And you can limit that to
bow hunting, during those seasons.)
It is very true, that wildlife officers will leave you alone, if you are not causing a problem. ...But the laws and regulations are very clear. If the wildlife officers don't like your attitude, they are well within the law to detain you. Whether they issue a warning, seize property, or cite you, is up to them. Does it really matter how strong their argument is, if you still have to be severely inconvenienced to fight any charges?
The point:
If you a responsible and courteous recreational shooter, you'll be fine.
If you're a jerk, the state has more than enough power to ruin your day (and then some).