Lessee... 0600 departure, 0500 showtime, 0400 wakeup (pretty early... at best an unusual rest cycle)... one controller working (attention divided by working both ground and local frequencies? Early takeoff clearance given due to light traffic?), short taxi route (divided attention between checklist and ATC?), first flight of the day checklist (not much time to get it done), short distance between the two runway thresholds, takeoff clearance acknowledged by "roger" ("Cleared for takeoff 22" might have caught the Captain's attention)... sounds like a prime example of an accident chain to me...

A very sad day. May God bless them and their families.