Jokes aside...
There's many things that a PLD can do in boss fights increases the value to the group.
You can master individual bosses with custom rotations and positions, sometimes enough to make the healer /kowtow your leetness.

Examples AK 1st boss - Bash/Silence rotation on thunder III ensure you stay at near 100% with just a regen and minor heals.
Coil Turn 2 - Silence rotation while sharing tanking roles with another tank (Highly stressful job).
Titan - 3rd Phase, Flashing exactly 3sec after land slide + casting stoneskin just before the 2nd punch hit, resulting the stoneskin up for mountain buster and taking less then 20% dmg or miss due to flash - your WHM will think you are a god.

If you sitting on just 1-2-3 combo spamming with most of your skills untouch then it's boring and your not doing your job well. Good PLDs always find something to put themselves at a advantage to the bosses, that's the fun part.