Like Bitxo said, when you start playing scenarios with objectives, that'll start to change how you play. It won't always be advantageous, or even possible, to mob up and run.
For a long time I've played with an extra thrown in that MWeaver came up with a while back. Adding a randomized amount of bodies to loot to any scenario, that have to be spread evenly across the board, and that includes evenly on different levels of play. Like if you roll that there are 6 bodies to loot, and you have buildings with 3 levels, 2 would have to be on the ground floor, 2 on the second, and 2 on the third, etc, etc. Its really helped with getting people to explore and move around a bit.
Note: this idea was shamelessly stolen from mweaver after i read about it being one of his solutions to get fighting to take place above ground level)
Before a game starts, each player rolls one d6, and the results are added together. The total number is the amount of dead bodies scattered across the board. The bodies must be spread evenly on the playing field, and must be evenly spread about the different floors of buildings. Whenever a member of a warband touches one of these bodies, roll a d6 and consult the following chart:
1 - THE UNDEAD!!!: The corpse has been reanimated as a zombie by the foul energy permeating the city. Using the Undead warbands stats for a single zombie, the body and the warband member are now in combat, which is resolved in initiative order.
2 - Waste of time: Nothing on the corpse but blood and tattered clothing. Move along, nothing to see here
3 - Got a lil' change in his pocket hasn't he?: the corpse has d6 GC on his person.
4 - Pretty well off weren't cha?: the corpse has 2d6x2 GC on his person.
5 - Well what do we 'ave 'ere?: the corpse has d3 Wyrdstone shards on his person.
6 - You sneaky monkey…: the corpse has d3 Wyrdstone shards, and a map of mordheim on his person.