I first came to manual lens because the kit lens have great limits, and my dad gave me its A50/1.7.
After few use of the prime, i realize that i needed more time to set up everything (aperture, framing, speed, etc ...), so i did less pictures, but they were far better.
I really enjoyed to go out for 2 or 3 hours, do only 30 shots and keep almost all of them because all were perfect. The full manual constraint force me to be better.
And i love LBA, and it's cheap.
But make no mistake, i really like good AF lenses, like the DA40
In short : people go for manual lens first because it's cheap, then because its fun !