Longevity lowers the cooldown on pet specials, including family specials like rake and monstrous bite, and even tree specials like Call of the Wild and Rabid. These add up.
As for mortal Shots, it's not a loss of 12% crit damage, but the crit BONUS is lower by comparison. At 2/5 Mortal Shots a crit hits for 212% damage. At 4/5 it is 224%. A 1000 damage shot is 2120 and 2240, respectively. The 2/5 Mortal Shots crit is only 5.4% lower than the 4/5 one.
But the reason people don't always max mortal shots is because mortal shots doesn't apply to most of the damage that BM hunters do. It doesn't apply to pet damage (which is why longevity can be a better option) and it doesn't apply to auto shot or serpent sting. It only is a factor on crit damage (which is a factor of crit rate, naturally), whereas some other talents increase certain damage all the time.
If people bothered to actually test out different builds in the spreadsheet, then they might understand why people make certain choices. There is a lot of math that the spreadsheet does for you, and sometimes a talent can be better than another at one level of gear or buffs and worse at the next. It's one thing to theorycraft the numbers yourself and seek clarification when the results show something you didn't expect, but it's another to just ignore several pages of math and analysis and just post off the cuff.
The spreadsheet shows Rosa's posted build as more dps than yours on every character that I have imported into it, including yours.
U are right and tks for reply my post... We tend to give opinions (me) without testing them and, sometimes, we (I) dont realy read the spell tooltip... my bad and tks for the info