I agree with you and Richard if it was my wall I'd re-plaster them myself too ..
I just assumed from gille's post here in the painting & decorating section a cheap/quick 'decorators fix ' was sought...
Two 1/2"layers - definitley not beyond the capabilities of Easifill on cracks illustrated by gille's photos... Obviously anything wider would require plasrteing :roll:
Ive never had a problem with it.
Its no use in gaps wider than about 2-3 mm
Make sure you buy a decent trade brand , not the thin stuff from a DIY store.
Jam a suitably-sized piece of wood in the hole just below surface level then apply a filler such as Tetrion or Easifill up to the wall level ..Once the lining papers covered it you wont know its there :wink: