Whilst I appreciate that times are tough in our industry and that commercial considerations / saving money are important, I get the feeling that things get a little distorted occaisionally. If you land with say CMR (company min reserve = diversion + 30 mins hold) then you have run an extremely efficient operation with no waste and it's all legal.
However you have also painted yourself into a corner in the event of something unforseen - missed approach, runway blocked, tech prob with the aircraft which need 5 mins to sort out. Fuel is money but it is also TIME. If you're rushed/distracted/pressured due to low fuel and then screw up your unforseen flapless approach who is to blame? What price bad publicity?
Further, carrying extra fuel would only be wasteful if, after landing, it was drained out of the aircraft and thrown away - the fuel is there for the next sector. Ok so may be you burn 10% of any extra by carrying it, so if you land with 500 kgs over minima you've burnt 50kgs to carry it - cost approx £10 / $16. What price a diversion (or worse)? I thinks it's fair to say that £10 in the scale of things in our industry is trivial (yes I appreciate that this is a cumulative cost directly related to the number of sectors flown) but in terms of the direct operating cost of an aircraft per sector my personal opinion is that £10 is good value if it prevents a diversion/mistake.
Obviously destination and time of day require other considerations but even if landing at 0300 with a "straight in, no delay" I still carry 10 -15 mins "go around or thinking time".
Keep it safe. A4