Theoretically there's nothing wrong with having quarterly status reports. Congress is supposed to oversee stuff and it may help focus the war effort.
But in the political/spin context ....
Politically, the Senate vote was not supportive of the WH. It was a CYA/compromise effort by the majority of senators and it was the GOP alterative to the Dems bill (a fixed timetable for withdrawal), which was defeated. The WH has already been giving status reports on a regular basis to Congress. What Bush needed from the Senate was a vote of confidence that we will stay the course.