I am guilty of loving "Superhero Movie"
Airplane! and Naked Gun though
Those are actually good parody movies but since 2000s parody movie quality has went downhill. But why people still make it?
Money of course
Doesn't cost much to make and those things rake in a lot of money
1. Scary Movie (2000) - Budget: 19mil Gross: 278mil
2. Scary Movie V (2013) - Budget: 14mil Gross: 78mil
3. Superhero Movie (2009) - Budget: 9mil Gross: 71mil
4. Vampires Suck (2010) - Budget: 12mil Gross: 80mil
5. Johnny English Strikes Again (2018) - Budget: 25mil Gross: 158mil
Courtesy of Box Office Mojo. Doesn't account for physical copies like DVD/ blu ray, streaming, VOD, etc.
Traditionally, movies need to make at least 150% of their budget back to break even, these things make more than that.
Same reason why there are a lot of horror films every year (which makes it probably the most successful genre in movies)