Flight plan fuel is a Minimum, it is normal to take more, in case of an airport like MAD in summer, it is normal to take A LOT more. it doesn't make a difference really anyhow, for the B737, an extra ton of fuel result of a burn that is a mere 30 to 50 kg. Higher per hour.
The company culture of not being absolutely free how much fuel to take, and having to defend yourself for doing,is at fault, not the crew who is brainwashed into O Leary Ryanair Borgs without a spine. Proof is the 2 previous posts, both by coincidence seem to live in Ireland...