Well, contrary to ruddiger's analysis, I think it's an interesting question.
You mean like
Cooper
Porter
Turner
Prosser
Hatcher
Fisher
Walker
Thatcher
Weaver
Roper
Tiller
Messenger
Staker
Treacher
Cocker
Blower
Draper
and
Reaper?
I reckon it's probably to do with invoking the image of a traditional close-knit country community. These types of names are traditionally associated with crafts or trades
e.g.
Cooper = barrel maker
Porter = doorkeeper
Turner = lathe worker
Walker = a person who walks on damp raw cloth in order to thicken it.
Thatcher = person who thatches roofs
Weaver = weaver
Draper = maker or seller of woolen cloth
The similar sounding names give a sense of Simon Pegg's character being an outsider.
Also, being associated with mundane worldly activities they contrast with his other-worldly name, Angel, and also with the name of the other guy who was onto the crooks - the reporter Tim Messenger ('angel' means 'messenger').
Really; some people don't like to think too much about films! They just want some entertainment. I think it's sometimes interesting to appreciate the skill and work of the writers & film makers.
