Personally, I don't permit the offensive version of Wall of Force.
Two reasons:
Firstly, it's easily worth of 5th level status as a utility/defensive spell. Need a time-out from combat to buff yourself, or for the cleric to heal the wounded, or have a few Delayed Blast Fireballs ready? Use Wall of Force (getting people to gather round if need be). In conjunction with Ghostform and/or Haste, it's a great tactical spell (Ghostform= hemisphere, go through the floor; Haste=cast spell then WoF). As a utility spell, it's also great. If the enemies are battering down the doors, Arcane Lock may not do the trick (especially if the enemy are Power Attacking greataxe-wielding barbarians); Wall of Force will plug the gap nicely.
Secondly, there are other spells which pull this trick. Otiluke's Resilient Sphere at 4th level permits a save; Forcecage at 7th level does not. There is no way that I would permit a 5th level spell to do what a 7th level spell does, especially given the material component cost of Forcecage. Since there is no save specified in the text of WoF, it is implicit therefore that the designer did not intend it to be used offensively. They surely couldn't be that stupid.