Since you’re basically asking for “fair matchups”, that can’t ever be achieved reliably as things are now. Because many people play WoW better as a whole now than they did back then. A big part of that is due to pserver-players explaining what to do and shaping the meta based on what they say, before Classic was even launched.
The other point of random matchmaking is that it can’t take into account skill. To begin with, for a matchmaking to take into account the skill of both sides, there needs to be a way to quantify it.
Inb4 you might say “just base the matchmaking on ilvl”, is that it would severely affect queue times and have a negative impact on everyone.
This is what a rating system is for. Rating systems, and why they started using it in Chess which is what all games today base their rating systems on, is that it’s a mathematical way to quantify “skill”.
Glicko RD is an example of a rating system with a rating deviation (just like the MMR being different from the CR in retail), while the Elo system is rather rudimentary in comparison.
This is why after Vanilla, they redesigned the entire reward scheme to separate the ones “seeking a challenge” to prefer the rating systems of arenas, and later RBGs, from the ones seeking that “casual, laidback experience” which many people queue random battlegrounds for in retail.
But you can’t just arbitrarily put in a rating system without changing the entire reward scheme to fit into it.
This is why, no matter if it’s premades vs. premades, premades vs. pugs, or pugs vs. pugs, it’s entirely random how well that goes.
They even changed the class designs to make players feel more empowered (and subsequently not die as fast) to make all these randomly matchmade encounters “feel more even” after a while.
Oh right, almost forgot:
It’s not so bad now, but the impact the gear is going to make in BGs is only going to get increasingly worse from now on. The difference between pre-raid and t1 isn’t so big, while the difference between pre-raid and t2 is slightly larger, while the difference between pre-raid and t3 is HUGE.
Eventually, this is going to make these randomly matchmade encounters in BGs be HEAVILY influenced by the amount of people with the highest tier of gear on each side. Regardless if this would be premade vs. premade or pug vs. pug, gear is going to make it go EVEN FASTER than it does now, and make you feel even more stomped than you do now if your gear isn’t “up to par”.