It's a good decision, you are putting safety first. Life happens, and sometimes it happens to grownups, too. People who are against reins (what they are really called, BTW) almost never think about what would happen to the child in a crowd if something happened to unavoidably distract the accompanying adult.
I'll give you a real-world example that happened to my mom. (Apologies to those who have read this story before.) Mom was walking along a very busy street that happened to be on a slope, when suddenly she tripped and fell, knocking herself out and breaking her ankle. My sister was 3 (on reins) and my brother was an infant in a big stroller. Mom lost her grip on the stroller, and it careened straight into traffic and caused several accidents, though by some miracle, none of the cars actually hit the stroller, and my brother wasn't hurt. However, the stroller had rolled so far that no one realized where it had come from, and the police took him to a different hospital than the one my mom was taken to. It was hours before she found out what had happened to him. By contrast, my sister, wearing a harness and reins that were around Mom's wrist, could not go anywhere, and stayed right by Mom's side while an ambulance was called.