Gear to protect against hand injury in a crash
Thankfully I never ride without gloves. The light weight gloves with padded leather in the  palms is all you need - they are cheap, comfortable and effective - what more could you ask for. I had a crash after my bike was tampered with and the front wheel fell off. I am a programmer, and although I emptied the company first aid kit of dressings, and could not walk properly or bend my elbow for days, I could still type. Had I not been wearing gloves, I would have been off work for weeks.  

As I see it, if you damage the leather enough to make the gloves unserviceable, and walk away - keep walking - straight to you lottery shop. Leather is tough and slide - in my case the gloves, which took the full impact of my fall, had no visible damage - unlike my shoulder, elbow and hip.... 

Wearing big heavy gloves might protect you hands, but downhill riders and motorcyclists that wear these also wear full face helmets and body armour - unless you do the same you will come off and although your hands will be fine, the rest of you won't be. 

Any bone damage is a problem - if you don't want it, don't fall off. You can learn to fall to minimize injury - downhiller riders are the masters of this, question is - can you be bothered as the only real way to learn is to do it.... You could wear body armour but its no guarantee.....  

Edit: 
Since writing this many years ago, I have taken up Martial Arts with my children (I am over 50). The techniques taught have helped enormously in a couple Mountain biking falls I have had, including one where I went 'over the bars'.