Nostalrius Begins - Quality wow vanilla realm (1.12)

Is it worth it as a lvl 15 ish rogue going say Skinning/ Lw or is it better off in the long run going something like say Skinning and another gathering profession

There's nothing "crafter-only" about Leatherworking (those Bind-on-Creation recipes werent added until TBC), so there's nothing that cannot be made for you by another Leatherworker. So if you're interested purely in making money, Skinning/Herbalism or Skinning/Mining are better than Skinning/Leatherworking.

I would suggest you just go level to 60 first and worry about professions then.