I had no ill will toward Ben when I let him drop. I felt terrible for it afterward, so much so I was practically begging the game that no one would ask about Ben when we got back. The main reasons I did it were because:
1. I didn't actually think he could be saved. I thought he would be killed somehow, immediately after I pulled him up.
2. The walkers were practically to us. I didn't think there was even time to pull him up without putting myself and the rest of the group in severe danger.
3. He gave his consent. He faced his end bravely, and was willing to sacrifice himself so that everyone else could live.
After getting back to the house I almost rewound to try and save him because I felt so terrible. But that was on my canon save, where I stick with my choices no matter what.