Would be nice if you were punished for trying to skip past everything. Do what WoW does in its dungeons. Have different packs of enemies that have different abilities that will thoroughly wreck your fireteam if you don't handle them properly(so long as it isn't something lame as "this mob can only take damage from rocket launchers" sort of thing.) Some mechanical creativity would really breathe life into strikes, and curtail the whole "1 hunter runs ahead and kills everything while their teammates just hold the sprint button until the strike's over."