ATF was close to a budget increase and need a "big show" to warrant an increase in funding. They knew they had a weak case, but could put on a helluva a show for more of those $fedbucks$.
Never trust ATF. NEVER.
They even brought their long tables for the photo op.
F Troop was lucky the day of their initial assault. Had they been going up against a group with any real decent basic training at all they would have all been slaughtered. Instead of walking off carrying their wounded and dead they would have been ducking from heavy fire and dying.
This was a government screw up beginning to end. They easily had the nut job Koresh whenever they wanted him without a fight or siege, the government wanted a big show, well they got one and a lot of people got hurt and murdered for their big show.