Well, I would blame the FBI. Aren't they the ones who actually planned and conducted the raid?
As for who set the place on fire? The DOJ report claims the Davidians set the fire. Surviving Davidians said it happened during the assault. The independent investigation conducted by the Univ. of Maryland fire experts did not resolve that issue but they did conclude that the victims had adequate time and routes to egress and escape the fire had they chosen to. In other words, they chose to stay and burn.
I think they have learned some lessons in the past 30 years. More recent standoffs haven't ended the same way.