Well like you say, it helps to break down those 14 victories:
Great Britain 2008
As you can see there are few dud races. Hungary 2007 was more famous for what happened before the race, China 2008 was a drive into another postcode (as Charlie Cox would put it, you might have to get used to that one next year) and his 2009 wins were at boring tracks. In each case he comfortably had the best car on the day and a team-mate running further down, which will always produce a boring victory.
That leaves 10, some of which were wet, as you say: Japan 2007, Monaco 2008, Great Britain 2008 and Belgium 2010. All but the latter were conducted in pretty atrocious conditions for all or part of the race. These are conditions Hamilton has traditionally done very well in and tend to produce exciting races.
So that leaves 6. Canada 2007 and Australia 2008 were victories despite Safety Cars making a regular appearance, producing exciting races but also harder-fought wins (having your lead constantly eroded). Indianapolis was decided in a mid-race fight with Alonso where he superbly defended an overtaking manoeuvres into Turn 1. Germany 2008 was won from behind after McLaren gambled on leaving him out and bringing Kovalainen in to cover his race. Turkey 2010 saw the Red Bulls crash but also another fight with a team-mate. Canada 2010 saw changing track conditions and another fight, this time with Alonso.
So it seems he wins races where he pulls his socks up and gets the job done, like driving in the rain or racing for position. Which is of course exciting.