Kaivax, a WoW forum community manager, revealed that WoW Classic's class design, battleground mechanics and stats on existing items will be set to their 1.12 state, despite the game releasing content that expands beyond that. This removes "progressive itemization," so if the stats on a specific piece of equipment was changed during the original updates, that won't take effect in this version.
They seem to have expected some things, though, see adding pets with aquatic damage (gun and ooze) aswell as a resistant cockroach to stop us from cheesing everything with elementals. Yet, a fact their damage output is low combined with shields not checking for racial damage means this mechanic prevents a lot as you mentioned. The last boss has got an ability to remove basic shields so perhaps that was not in oblivion either… unlike the reactive damage. Also, an ability that forces swap altogether with an ability which prevents from being swapped, including critters? I can't say I like it.
Why Skinning? Skinning is incredibly easy to level up while you are leveling your character. The leather that you skin will almost always sell on the Auction House (albeit not for much, but hey– it’s free gold!). Even if you don’t want to take the effort to sell the skins on the Auction House, you can simply vendor them for a significant amount of extra gold.
And for talent builds. I prefer to make my own talent builds. But I've been playing RPGs since the 8bit days so half the fun is building my own characters up. I already made and bookmarked 1 deep fire mage build, 2 elemental mage builds, and 2 deep frost mage builds. And I might remake them tomorrow if I read up on any good talent choices I left out my 1st 5 times lol. And I have multiple builds for the other classes I play too.