Let's have some common sense please. Fuel regs dictate the absolute minimum fuel an a/c can depart with. The calculations are very reasonable. I've been doing this a long time, in many different airlines, in various CAA's jurisdiction and on various a/c for long & short-haul. Never had a problem with the regs. It gave me a minimum start datum. There has to be a minimum limit, just as there as maximum limits for other parameters in our operations. Using this datum and all the other relevant data given to us at dispatch I then made a reasoned decision on what to take. Often the minimum was sufficient, sometimes not. Calculating the extra was the skill. Airlines are a private sector business and see how many have gone bust. Out of control costs don't help. It's all about common sense, statistics, risk management etc. If the company considers the occasional diversion, either at destination or en-route, to be acceptable in the year long costs of its operation then I don't have a problem with that. One airline I flew with make a statistical analysis of its home base weather over a couple of years and decided it was not cost effective to have CAT 3 a/c. Thus they accepted the few diversions due to fog. It was a foggy airfield in Autumn, but the numbers said CAT 3 would not have been such a saving grace X% of the time, so we stayed at CAT 1. This was in the days when a/c were not standard CAT 2/3. Was that unsafe? No, it was sometimes inconvenient. Extra fuel to hang around was not a problem.
Long-haul into the Caribbean with 150kts jet streams, and NPA at destination and dodgy weather forecasting was not a time to be on minimum. One airline tried to tell us that 5% contingency for the 12 hour flight was enough. No it wasn't. A diversion delayed the return due to crew duty times etc. However, on the return to Europe the ground was littered with CAT 3 airfields from first landfall well before destination. Minimum was usually more than enough. It's having the knowledge to make a sensible calculation and feeling free to do so. Other than that then there is a safety issue. Legal minimum is just that: it may not always be the sensible choice.