You're right that most homebrewers brew ales and not lagers. If I took a guess, I'd say it's probably in the in the range of 70-80%. Those that brew lagers almost inevitably brew both ales and lagers.
Lagers aren't that much more complex to brew, if at all. To brew a lager well, you need a reliable temperature controlled fermentation environment, which is easiest done by a freezer and temperature controller (cost), but there are DIY ways to do it too.
Time is another big thing. The average ale only takes about 3-4 weeks to be drinkable (kegging) and 5-6 weeks (bottling). But the average lager takes double that. Lagers require patience and extra vessels.
For the brewing part, you can brew a lager with roughly the same procedures as brewing an ale, but since pilsner malt is often used, you need to do a 90 min. boil. It's also best to have the wort cooled more (</= 50°F) before pitching yeast. And since some of the best lager styles are German, decoction mashing is sometimes used (although not necessary).
The rewards are great, but are more of a personal accomplishment than anything. To take a drink of a clean, malty lager that you took so much care to make (e.g, decoction, 6 week lagering period, good temp. control, etc.) is very rewarding, but the full appreciation is yours alone.
Commercially, lagers are brewed far more than ales. This has to do with the advent of refrigeration in the mid-late 1800s and the industrial revolution, the influx of immigrant German brewers to the US, and the desire to make beer that the majority of people like (little yeast character, lightly hopped). These lager breweries grew and grew and eventually came to define what beer is to most Americans... cheap and widely available.
But brewing lagers at home can be much more rewarding than drinking a commercial example. Most commercial lagers are centrifuged, filtered, pasteurized (and consequently stripped of flavor and character) to have a longer shelf life and be more forgiving when mishandled. Homebrewed lagers are fresh and flavorful due to leaving in proteins and suspended yeast.
BigEd is right... brew what you like. If this were 150 years ago and we could homebrew the way we do today, we'd probably all be brewing lagers because of always having drank ales.