I've grinded many toons to 60 & only dropped one legendary item shortly after they were introduced, & it was while supporting another on conj. It's been my experience & I contend it is true, that drops as a system have had their %'s tinkered with over the last 2 years. Comparing then with now, it is by far no longer as easy to drop & what does drop is noticeably of poorer material quality &/or usually possesses inferior or undesired enchantment bonuses. This also seems to be the case with boxes as well over the same time period. The %'s tend to spit out crap with crap qualities. Simply put, it has increasingly & observably become much, much more difficult & expensive overall to obtain high quality gear with highly desired enchantment combinations of high lvl value thru grinding or boxing. As a result, I refuse to drop-grind or box at all anymore. Period
P.S.: yes, yes, to obi-fay u listen ... get any gears at all near your own lvl that have high slash & pierce resists & make do til better comes along. Tho some may disagree, armor resists are more important imho than bonus enchantments anyhoo'.