Most great goalscorers score a lot of penalties, and a lot of the time you'll find great goalscorers win most of these penalties themselves, I don't have the stats to hand but of the 14 penalties he took last season, I think Johnson was directly involved for about 8 or 9, often in positions where a man with his finishing ability (which can't be doubted) would have almost certainly scored. Discrediting penalties from a player's goalscoring record is ludicrous.
You can't ignore the simple fact that Johnson and Ashton played in sides of a very similar standard last season and when they were both playing in the Premiership, Johnson scored 12 to Ashton's 7. And he has only scored 5 times for West Ham thus far, which is not good enough to take a striker the World Cup - I touted his name about myself recently I must admit, but having looked into it, while I don't doubt he can score great goals and has a lot of talent, I would rather have Johnson in the team simply because he is good at being in the right place at the right time, and if it came down to it, in the 90th minute of a match, I know which player I'd rather have running into the 6 yard box to finish a move off - Johnson
Alas, Ashton's career record is slightly better (Johnson has 1 more goal from less appearances) but Johnson's record at Birmingham was poor, at Palace his record is slightly better than 0.5 goals per game
Each to their own, but as someone who grew up watching the mighty John Aldridge, I can't help but love someone who has a knack for scoring goals, however he happens to get them.