I have 3 chain hooks welded to the top of my FEL bucket, one on each end and one in the middle. I have a New Holland TC33DA with their standard quick attach bucket. I purchased the tractor new and had the dealer do this for me at the time of purchase. He didn't charge me anything for the hooks or the labor.
I've used the hooks several times and they're very handy. The top of my bucket seems beefy enough for the hooks, and there's no additional reinforcement.
I suppose if I tried to pull something really heavy I could bend or break something, but for most of the chores I encounter (pulling logs) I'm sure they're plenty heavy enough. I do use common sense such as pulling in a straight line, looping the chain through both end hooks if appropriate, etc.
My hooks are 5/16" "grade 70" (as are my chains) which are rated for 4700 lbs. This size chain was lighter and easier to handle than 3/8" and met my needs. You'll have to evaluate your loads and decide what makes sense for you.