Maybe they haven't got the right people to generate suitable reports.
I'm not indifferent to this argument. BUT;
1. Randomly select any 5 past reports and I'll bet that a final year engineering student could do better and
2. Most of the reports they do are not about serous accidents. Most are like one of the oldest outstanding report where a Seneca was directed to descend below LSALT by ATC. I doubt that one takes years of experience by trained investigators. It might take years of training to create the politically correct report - but that's hardly fitting the the "without fear or favour" mantra, is it?