It's definitely not a bad idea. Each property would be isolated from each other in the event of a lawsuit (assuming you run them properly). Downside is the cost and accounting hassle.
I've been recommended to have an LLC for properties in clumps. Hold 3-4 properties in each LLC, rather than 1 per. There really isn't a correct or incorrect way to do it (unless your commingling your assets with the LLCs which strips away the protections). Do whatever helps you sleep best at night and chalk up the $ spent towards the cost of doing business. Good luck!