I cleared Naxx world 4th in Vanilla. I don't think many of us at all were engineering. Keep in mind, people were mostly new to raiding in Vanilla (a few EQ people, I was from DAoC but WoW was very different) so people sucked... a lot of people clicked abilities, didn't use macros, didn't have programmable 12 button mice, etc, and we beat it. Vanilla raiding is very easy vs Mythic Wralords/Legion etc. I am all for min maxing - When it's needed. It is not needed for Vanilla content. People are going to blow through raids like a .50 rounds thought cardboard. NOBODY cares if you kill a boss in 90 seconds, or 95 seconds. Your time to get world firsts was 15-14 years ago... you missed the boat.
Engineering gives: Goblin Sapper Charge: 450-700 damage in fire, 5 min CD, and puts other explosives on CD. So yeah, if 40 people use it, 18k-28k damage. Do you really NEED to cheese Vanilla? Its like requiring people to to this in Normal/Heroic difficulty in live... why? If you can't beat it without little tricks you are the problem. Battle Chicken: Gives Battle Squak, 5% increased attack speed... but here is the thing: It takes up a trinket slot. There are some really nice trinkets out there already. Lastly, I have to go off memory of 14 years ago vs private server videos. In the videos I watched bosses drop in like 30 seconds. That doesn't look fun to me... like a warrior barely even gets to execute. You want it to be FASTER than that? If anything, bosses need like a 20% HP buff over Vanilla just because people know how to play now.
So to sum up:
Min maxing on Mythic difficulty for a tiny bonus on content that is not already widely understood going for a world first? - Yes, 100% understand.
Min maxing on content that is 1) Easy to begin with 2) Already beaten by 2006 3) Rebeaten 100's of times by people on private servers 4) People are much better overall now. - LoL No. You are trying to kill a mouse with a MOAB, it isn't needed.
Edit: Yeah you can equip the chicken trinket, use it right before the pull then put on a better trinket but again its just a pain that isn't needed for easy content.