...it is a very bad policy for beancounters to decide minimum fuel - way before the crew signs in.
Paranoid Rubbish! Minimum fuel is exactly what it says. It's nothing to do with bean counting. It is a figure which meets all legal requirements in the given conditions. As part of the planning information, we are also given statistical information which tells us how much the average flight varies from the plan and the mean difference in fuel. So, if we wish, we can sometimes depart with LESS than "planned" fuel. But without the planning, how can I possibly calculate how much fuel I really need? It also means I don't HAVE call the refueller back for a prattish 30 kgs. It is no different to performance planning. The bean counters tell me how much I can lift from certain runway under given conditions - so should I use their numbers or my own?
What I actually do on the day all depends... That's what I'm paid for. But let's make no mistake. We as a crew make our own decisions, not the company.
And while we are here - over the last couple of years (500 flights/year) I've only ever flown with 'extra' fuel on a handful of flights. The vast majority of flights I depart with what might be described as "Minimum Fuel" and have only once felt anxious. That was not because it was unsafe but because I felt we might have to divert and would not get our passengers to where they wanted to be.