I don't call camping cheap and boring because I'm some kind of untouchable god, I'm speaking from experiences in KF1.
Every time I joined servers running difficulties above hard, it was an absolute snooze-fest. On a team of six it only took four people to hold back the zeds so effectively that none ever made it INTO the room, and one of those people was a Sharpshooter who literally did
nothing unless a FP showed up.
So that's one player who got to shoot at ~3 zeds
per wave, a berzerker whose entire job was to stay crouched and hold M1 in the doorway, a medic whose entire job was just to sit there and heal the 'zerker, and maybe one commando or support firing over the 'zerker's shoulder or shooing away the occasional slippery crawler or stalker.
That's not an action-packed shooter. That's not co-op horror survival or
anything else Killing Floor is supposed to be. That's the world's most easy and tedious
Tower Defense.
But that was KF1 and I'm really starting to think this is already much less of a problem in KF2 (ESPECIALLY above Normal). All of the camp-able rooms have
some vents or such for zeds to sneak in through. Welding up some doors can make a room
temporarily easy to hold.. but sometimes only long enough that everyone can get healed back up before things get too hairy again. Stalkers are harder to see (without commando help) and sneakier than ever, and FPs and Scrakes can't be taken down so easily that they won't wreck a secure formation and cause serious chaos (at least not until we get some specific other perks available)
Even when we set out to hold down a secure spot, it's pretty often that we have to migrate somewhere else in the middle of a wave anyhow.. Or we'll start out on the move and in order to catch our breath we'll have to slam a door in some zeds' faces and hole up somewhere (because they aren't as slow and shambly as they used to be!)
I don't know yet how people are playing KF2 in Suicidal and HoE but if Hard is any indication, the balance of camping and mobility is actually pretty good right now.
(Trying to 100% kite the zeds almost never ends well for a team, on the other hand)