Necromancers, Mesmers, and sometimes (but rarely) rangers are often looked upon as "optional" characters for a group. Rangers usually don't have a problem, especially with UW/Fissure because of their traps, but elsewhere they're sometimes overlooked. I'll focus on Memsers and Necromancers though.
The problem with necromancers and memsers is that they work in the background, they might have some pretty wicked magic but they work with it behind the scenes, while the tanks are up there taking hits and the elementalists are nuking, you obviously notice them a lot. Elementists magic is most often direct damage (usually with a cool affect that MAKES you notice as well) and warriors can't be ignored the way they run up first, monks obviously are necessary in a party (...usually) and they always get noticed by the warriors who're getting hurt. These three classes are noticed most. Rangers also sort of fit into this category because their traps and other skills are pretty noticable.
Where as these characters all work directly and do a certain job, mesmers and necromancers are much more about working on a different sense, they don't just go out and do damage they're typically your background support characters, and the damage they deal isn't often noticed because it's either enemy-action dependant or it's DoT. For necromancers the only skills that people actually SEE are wells and animated minions being summoned.
Little do other people know, a good necromancer (or mesmer) can definately change the tide of any battle. I remember our group was having loads of trouble with Elona Reach until I brought my necromancer along where we did it our first time trying. See necros and mesmers just...go through the battles and pull their strings when they see the right moments, they work their magic on a behind-the-scenes level. Mesmers are the same way, except they've usually got a set job and people know what they do.
I would honestly have to say that out of all the classes in GW, Necromancers are hardest to play well. I've gone through the game with every profession now and my necromancer has been hardest to master.
I've changed my necros secondary profession 5 times just trying to find out the best build! My mesmer---not a problem to get good with, he was my first character I went through the game with and never did I have a problem figuring out a good build and using those skills to their best benefits. My ranger, not a problem either, a simple mass-condition OR mass-damage build was all it took, not a big deal. Warrior? Also simple, I could go many ways with that guy, could go with an aftershock warrior, a warrior with some helpful smiting, whatever I wanted, people always needed a good tank. Monk? Heal, protect, simple enough. Never had a problem unless some dumbass went off out of my range.
But the necromancer...just what could I do? A N/W was a possibility but the time it took to get off certain hexes on a warrior to take him down kinda sucked, and it was difficult to fend off more than one warrior at a time, not only was your armor not as good but the monks on your team wouldn't ever bother to heal you, the lowly necromancer. A simple DoT build? Meh...not all that great, DoTs are alright if you can always keep them going but a good healing breeze can nearly stop a max health degeneration if not stop it entirely. Curses? Well..., sure it's great to weaken, slow the attack of, and give -20 armor to a warrior...but then who will kill it? Warriors aren't often the first ones to be attacked, and since you can't likely do it yourself that's a no-go. Death magic summons? Good for PvE in a sense, but they don't work against anything that doesn't leave a fleshy corpse often leaving you short handed, and to keep a good army going it takes up almost your entire skill bar. And something that dependant on enemy corpses is too reliant on something other than your own skill. Blood magic? Pretty good...but finding the right skills from your secondary or other necro lines to mix it with is the problem, blood on its own is pretty easily countered.
Sure some of things I listed above work alright, but they aren't NECESSARY (at least as seen by most people) in a group unless you spam all your wells to help THEM do the work. They have to kill the monsters, they need the health/energy, all you do is...put up the wells, and their happy. And wells are the only sort of skill they'll even know you're using.
It's a shame, really. Necromancers are a tough class to master, and there are A LOT of necromancers out there who're pretty...dumb, and just don't play their professions very effectively. This spreading the generalization that necros are an "optional" class.
Someone who can pull off a great combination with a necromancer is a damn good player in himself (herself), and should always be looked upon as a valuable asset to any team.
People don't know of the necromancer's true abilities until they've really tried to master one themself, and that's the bad part, because when they do try they can't often pull it off well...so people think they're bad.
Go necromancers!
