I remember being a child and my parents being hesitant to buy certain books for me. They thought maybe I would read them once and never pick them up again, or maybe just they weren't very good books in the first place.
They may have been right. But they definitely should not have questioned me about them. I was a kid who did not like reading much. It was a fight to get me to read the books we had to read for school (and that pretty much persisted through high school), so if there was anything that I actively wanted to go out and read, it should have been encouraged.
I really believe that we should support anything that gets people (especially children) to read. I would hope that it's not godawful trash like the Twilight series, but even then, I would rather have people reading trash than nothing.
Nobody magically is born with good taste; it's developed and refined over time. If somebody does not like reading, they are missing out. So if a person needs to read some terrible story in order to develop a fondness for the written word, so be it. Over time, they will find more stories. They will develop a sense of quality and will filter out stories that don't have enough.
For me, it's simple: Anything for them to read.