Maybe the aim implant doesn't count for skill level or something? I think it's a combination of your skill levels, health and weapon wielded that determines whether you get targeted, but admittedly that's a guess.
This is the character I was playing when Grim implemented those changes and he's been the target of every enemy 'Advanced Tactics' volley. He would have had all health implants and more than 100 RC and MC and even when going into battle with only a powered Katana he's always been singled out for punishment by my opponents.
Could be. I usually start with a scientist build and I always buy the aim implant so I never have a reason to train up ranged. It just goes up on it's own via combat and since I never miss because of the implant I don't care if it's 50 or 150. I tend to spend more time doing melee so even though my ranged usually starts off higher than my melee, my melee always overtakes it relatively soon.
I generally pick up Ansel, Peasant, Loren, and Rifle Savant on day 1 to do a few easy fights and the bounty if it's a tier 1 or 2. I never really paid attention to who gets targeted for that day 1 bounty since I usually refuse anything above a tier 2 on day 1. Day 2 I replace Rifle Savant and Peasant with Dexter and Doyle, and Doyle definitely becomes the tank for bounties immediately.
Usually by day 4 I've unlocked Crystal Hills so I go pick up Ayden, at which point he becomes the new tank for a couple of weeks. When I see my first tier 5 bounty I pick up Connor, but Ayden seems to remain the tank until Connor gets a plasma gun, at which point Connor becomes the main tank.
So early on at least, the weapon being used seems to play a big part in who the game picks as tank. Any merc with a plasma gun seems to get picked over Ayden in my game which generally means that by the time I make it to fighting tier 6 bounties my first 2 tanks are Connor and Felix, not necessarily in that order. In fact the game seems to usually pick Felix over Connor as the main tank even though both have plasma guns and Connor has better stats.
I do use a plasma gun on my main for the tier 6 bounties but even with 200 health my main does not get targeted, in fact in my last game Bud actually got targetted before my main (both of us had plasma guns and Bud had higher ranged skill than me because I trained him).
Slaves are different, especially if you give them stealth suits. If I'm running with 4 slaves then they're all going to have stealth suits and that means my MC is going to take all the damage. But I rarely do that, and never until several months in. Those stealth suits are expensive. I usually will pick up some combat weave for 1 slave around the end of week 1 so I can start working on respect with the girls, just rotating each slave in 1 at a time to get them all to 20 respect.
Maybe since I tend to pick up at least 1 or 2 of the top tiers pretty early they're just naturally going to stay ahead of my main's stats when it comes to ranged skill? Not sure about strength or dex. I do train those up but not until at least a few months into the game. Stamina I boost to over 100 immediately though.