Pulling a trailer slows you down. The more baggage you have, the slower you can move. This is fine, if you're carrying stuff you want, but often you're carrying boxes filled with things you can't even remember. Be sure that what you're carrying is what you really need and want, and not just baggage you've carried from place to place to place and never really opened.
Going slow can be a pleasant experience. On the way, we were passed by many, many, many cars. And trucks. And bikes. And everything else on the road. In fact, it was so commonplace to be passed that when we ourselves passed someone else we cheered (small things entertain you on a long drive). But what our trailer taught us is that all those people passing by us were going to get to their destination maybe an hour or two earlier, and in the meantime they were pushing their cars, using more gas, and having to keep an eye out for cops. Not having to worry about any of those ended up making for quite a pleasant journey, and even with the heavy trailer, we used less gas than usual, going our whopping 55 mph for 25 hours...
The more baggage you tow, the less control you have. We passed several wrecks on the way, all (except for one) involving trailers of some sort. If you have a lot of baggage, you have to slow down in order to exert control over your situation. Sudden changes are not easy to handle when you're pulling a heavy load or carrying a lot of baggage, because your reactions are bogged down by the weight of it all. Lighten your load, and your reaction time and ability improve dramatically.
Don't make assumptions about what other people are pulling. Their trailer might be light, but it also might be extremely heavy. We had several near-misses by cars pulling in front of us or braking unnecessarily, not realizing that our reaction time was limited. Don't "pull in front of" someone else and assume they can react quickly and appropriately. The more baggage they're carrying, the harder it is for them to avoid a crash.
And the last lesson our friendly U-Haul taught us is that we humans are adaptable beings. We adapt to change. Our car wasn't too thrilled by the load it was having to pull, but it did a wonderful job. And we, too, got used to seeing that big ol' trailer behind us. I'm glad we did, because if we hadn't, we might never have heard all it had to say, and what a conversationalist it turned out to be!