One of the best uses of a lens hood is to protect your expensive lens. This way should you accidentally bash your lens into something or someone, the lens hood would take the brunt of the damage. Which would your rather replace? A thirty dollar lens hood or a thousand dollar lens?
Another use for a lens hood is to help reduce lens flare and provide for a better picture color wise. Of course, if you are shooting macros inside a studio environment then a lens hood is probably not as important. But for outdoor shots, it may help to enhance your photos.
On the other hand, lens hoods can be a bit inconvenient. For one thing, for a simple piece of plastic, some of these lens hoods seem to cost a little too much. Fortunately, if you buy L-grade lenses, then they should come with a decent lens hood. But if you ever need to replace it, you will have to cough up around ten to forty dollars. Which, again, really is not that bad if you bought an expensive lens.
Lens hoods are bulky. They tend to be a bit of a pain to stow away in your luggage, which may make some photographers hesitant to bring them on trips. Keep in mind that you can reverse the lens hood, and wrap it around the lens. This helps to free up room in your camera bag. But these lens hoods will still take up a lot of room.
If you have a lens filter attached to your camera lens, then that might interfere with your ability to use a lens hood. Utilizing both a filter and a lens hood is usually fine; however, just make sure the two do not interfere with each other.
Unfortunately, using a lens hood will make you stand out a little bit in a crowd of people. This could increase the odds of your gear being targeted by criminals. Then again, if you own L grade glass, you probably already attract the same type of attention that a lens hood would bring. Especially, if you own something like the Canon 100-400mm. It is a large white lens that definitely stands out in a crowd.
Lens hoods have their positives and negatives. But in the end, it is up to each individual photographer to decide what works best for them. ©JR All Rights Reserved