To what extent have you factored-in capacities? The majority of EPL clubs are currently playing to full or almost full houses every game. Who knows what attendances might be if their ground capacities were at the same level as those in Germany.
You've chosen to exemplify Wigan and QPR as clubs that do not sell out every game. We all know that Wigan is predominantly a Rugby League area and anyway the town itself (as opposed to the District, which embraces smaller towns and villages up to ten miles distant) has a relatively small population - around 81,000 in 2001. So an average of 18,000 on that population is none too bad.
As to QPR, yes they ought to be packing their ground every game, but their current average at 17,692 is only c.600 below available capacity. Current official capacity is 18,439 but segregation / safety issues probably reduce this to around 18,300.
I've been doing some calculations and despite what you say about the way British clubs treat their fans, Premiership gates this season appear to be closer to capacity overall than they have ever been:
Average attendances 2012-13 as percentage of available capacity*
99.99% - Fulham
99.89% - Arsenal
99.67% - Reading
99.55% - Manchester United
99.52% - Chelsea
99.51% - Swansea City
99.49% - Norwich City
99.23% - Liverpool
99.21% - Tottenham Hotspur
98.21% - Emirates Marketing Project
97.76% - West Ham United
97.62% - Stoke City
96.88% - Queens Park Rangers
96.19% - Saudi Sportswashing Machine
94.71% - West Bromwich Albion
93.85% - Southampton
93.69% - Everton
87.10% - Sunderland
80.77% - Aston Villa
74.10% - Wigan Athletic
*As of 09/11/2012. Percentage of available capacity is based on current official capacity as provided by the official site of the Barclays Premier League, minus allowance for segregation and safety. In truth there are no official statistics for such capacities, which seem to vary from club to club and in some instances from game to game. But it is possible to arrive at a well-informed guesstimate for each club based on their highest attendances, sell-out after sell-out. This is what has been attempted here.
Sources:
Official Capacities:
http://www.premierleague.com/en-gb.html
Average attendances, 2012/13
http://soccernet.espn.go.com/stats/attendance/_/league/eng.1/barclays-premier-league?cc=5739#
(Click on each club to find results and attendances game by game, season by season)
Highest all-seater attendances
http://footballgroundguide.ipbhost.com/index.php?showtopic=1100