Guardians are by no means underpowered. I always cringe when people complain about what is hands-down the best group support/spearhead in any content because it doesn’t play like another profession. Some of us have been main guardian from the start and we have builds that haven’t changed in over a year in PVE and PVP.
The idea that all professions can be equally good at every aspect of play is just a fantasy. ArenaNet made a big deal of muddying the water, but the truth is that any game which has mechanically different classes will have incomparables which cannot be so easily balanced and will leave some better at specific things than others.