I just bought such a trailer from Harbor Freight. I've already had a tow hitch installed on my car, I just have to assemble the trailer and get it licensed. (Received the title in the mail yesterday.)
So, clearly, I think this will be useful. I intend to use it for building supplies. Things like sheet rock, hardie board siding, 2x4s, plywood, etc. I'll still have major deliveries delivered because it's a better usage of my time vs. the cost to have thousands of dollars worth of stuff delivered at one time.
But let me tell you a story of a trip I made some years back. I wanted to put in 3/4" hardwood flooring into my home in Atlanta. I had found a factory distributor about 60 miles away where I could get a much, much better price. So I rented a small uhaul trailer and drove up to the store. I loaded it up with a bit of trepidation and started my drive home down I-75. I stayed in the right lane and traveled at the minimum allowable speed, 45mph. I felt quite safe.
I was dead wrong. I just didn't know it and I got lucky. I guess that makes it "alive wrong".
As I got closer to Atlanta I hit some stop and go traffic. The traffic stopped suddenly when I didn't expect it. I was going 15 miles per hour. I slammed on the brakes.
The weight in the UHaul lifted my car's tires up in the air high enough that they no longer provided any traction of any sort. My car just kept moving as the inertia in that load pushed it forward.
God help me if I had tried to suddenly change speed or direction at any higher speed.
So, multiple trips to the store and back are better than one trip with a very heavy load.