I probably shouldn't tell you about crawling under the brush hog to unwind fence wire ( would have had to drive all the way back to the barn to prop it) or lifting the loader part way up to grease it. I think this falls under the heading of "Acceptable Risk".
If the hydraulics were to fail as you're under the brush hog or the loader you'd be thinking differently... in a hurry.
As far as "Acceptable Risk" is concerned, I think risks such as the one's you cited are easily mitigated by planning ahead. You know you may encounter fence wire when brush hogging so having something to prop it up with (just in case) would mitigate that risk, with the same being true for working on the loader.