jeffmartin043, thanks so much for posting!
I have some good news, and some bad news:
The good news is that all of your logical analysis is absolutely rock solid! The premise establishes that highly visible burglar alarms make getting robbed less likely, and anything that makes getting robbed less likely is a useful thing. This absolutely could support a conclusion that all highly visible burglar alarms are useful!
The bad news is that that isn't what the incorrect conclusion actually said!
This question tests your attention to detail the same way the LSAT will, by introducing a detail shift that your mind is likely to simply gloss over ('mental spackle'!).
The incorrect conclusion is actually about ALL VISIBLE burglar alarms, not just all HIGHLY visible burglar alarms! That's a potentially much broader category, and we don't have any information to support a claim about the entire category of visible burglar alarms - just the
highly visible ones!
It's so easy to misread that incorrect conclusion as if it had the word "highly" in it - we add in the words that we expect to be there, and the LSAT knows it. Sneaky devils. This is a test in making your radar for term shifts much more sensitive!
Does that help clear things up a bit?