Two fold response.
1. Optics. The shock and awe is a smart tactic because the detractors perpetually claim Trump is all bluster. Look at all the sniffling over egg prices and Ukraine. Releasing the DOGE with a mission of immediate results not only shapes the narrative but also, y'know, gets results. But that's political strategery and not my favorite thing.
2. Urgency. Trump has four years. A slow methodical navel-gaze only allows nonsupporters to run out rhe clock. Case and point, all the Mueller garbage and impeachment hearings. Trump, naievly, tried to play by the establishments rulea last time. My assumption is that now he sees the folly of doing that again. The country needs to be handled like a patient who just stumbled into the ER, bleeding and vomiting. Stabilize first, observe as you go, diagnose second.
Musk already said DOGE won't be perfect. They'll assess as they go and turn funding back on where it's merited. A reporter tried to call him out on the error in the DOGE claim $50MM was spent on condoms for Gaza. Oops. Turns out those were condoms for Mozambique. Musk admitted the error, but then pointed out that $50M in condoms is ridiculous no matter who the recipient.