Maybe this should go into a bug report, but I wanted to discuss it here instead. Don't get me wrong, because I love skirmishes, and I'd rather have them, problems and all, than not have them.
Still, group size offensive skirmishes require a tank of some kind. I suppose I should of kind of sort of expected this but no, a heavy armor player is not ok, they require a serious tank with serious agro maintenance capabilities. period. No a beefed up soldier tank, or a whole army of beefed up soldier tanks will not work for long enough. This kind of makes them totally unfeasible for many group combinations and while it does make guardians more valuable, it negates the "popcorn" value of skirmishes. The bosses are just too hard. This is played at several levels below too. Group size ones are hard. Be warned.
Three man skirmishes do not require a tank. This leads you to believe the pattern will continue. I'm sure though that raid size skirmishes probably require two tanks at least, one for each group.
Solo skirmishes have too much of "more of the same" thing going on. More and more of the same enemies hurl themselves at you in an exercise in boredom. Playing with others mitigates this effect.
Easy solution, make the solo skirmishes more interesting, as the book chapters are for instance. (See book 7 for example or book 9) Oh wait they already did that one, nevermind...
Last problem, some classes have big problems with skirmishes. Burglars cannot sneak up on people with a companion giving them away, Hunters need lots of prep time between fights, and don't tank well, Tanks dont kill targets fast enough when you start pushing the envelope on difficulty. Yadda yadda yadda. Fortunately, skirmishes weren't meant to be the end all thingy anyways, but they work well all things considered.
I personally can't wait for a PvMP skirmish to arrive of some kind. The sooner the better.