Ok, standard wrist guards don't seem to be that helpful. But there seems to be a bit of misinformation on this thread, painting all wrist guards as the same. Flexmeter wrist guards solve many of the aforementioned problems (disclosure: I wear them).
These things were a god send for me after I broke my wrist: Flexmeter single sided wrist guards
I'm just going to copy a post I wrote recently somewhere else:
The concept behind these things is great. They allow your wrists to move and flex, while progressively
hardening on impact. Designed by a trauma surgeon in France, who was experiencing far too many wrist injuries in his ER for his liking. Here's some more info from the company itself: Flexmeter wrist guards for snowboarders and skaters
Two points to note:
1. You only need the single sided, as the double sided is more for skateboarding. It's too hard to fit a double sided under your gloves (unless, of course, you buy their gloves with the inserts already in).
2. The only complaint people have is they sometimes don't fit well under certain gloves. This can be dealt with by finding a pair that fits with the guards (I have always used Dakine Titan mittens, and the flexmeters fit fine with my medium mitts). Alternatively, you can size up your gloves, and it's no issue. Just avoid tight gloves, or gloves with elastic.
I broke my wrist and had to get some guards for support. These were the go and they haven't left my wrists since. They work as advertised. They are super light weight and don't feel restrictive. Your wrist and bones are free to move. Also, they don't transfer the force up the arm like other stiff wrist guards.