Many players (including me) have expressed a desire to see the playstyle of a Diablo Demon Hunter in WoW.
For me, the main difference between a Diablo Demon Hunter and a WoW Hunter is that the Demon Hunter does not have as significant a reliance on pets.
WoW designers have expressed having difficulty inventing a compelling identities for Hunter specs, especially some clear distinction between Marksmanship and Survival. Beast Mastery has a clear identity - its reliance on the pet - but Marksmanship and Survival struggle to differentiate themselves.
Would you want one of the Hunter specs - either Marksmanship or Survival - to differentiate itself by de-emphasizing the pet?
Whichever spec is chosen would lose the permanent pet, but would continue to have access to pets during cooldowns (e.g. Stampede). The Hunter would instead gain increased personal damage, and increased utility to compensate for the loss of a permanent pet.