I've encountered a couple JD dealers that didn't "like" the 5003 series tractors myself. I'm fairly certain that's because they want to sell a more expensive model in it's place. I have a "Golf Course Contractor" working for me right now, here at work, who has 22 John Deere tractors on site. He has 5400's, 5310's, 5420's 5320's, and a few (various models) of the 5003 series. He uses them HARD. (Temporary labor force operators) The XX03 series tractors have proven themselves under fire, as just as good, if not BETTER than some other 5000 series tractors. They don't have all the bells and whistles, but they seem to be a good, solid small tractor.
I'd say Mother Deere needs to get her dealers motivated to sell more of 'em. They might regain a big portion of market share they've been loosing by doing such.