LFG System Options
Nah…
If some guildmates want to participate in a dungeon, all they have to do is be on your party before using the LFG system.
Also, the whole idea of GW2 is that there is no holy trinity, and that translates to “I should never have to ask for a specific class in a group!”. The Mesmer already has a huge advantage when forming groups for jp, and if there is a case where a certain profession is unwanted in groups for whatever reason, rest assure that A-net will balance it in a patch.
…and don’t be toxic!