Lol, I'm not theorycrafting, I've been running PF1 for my group for about 8 years now along with plenty of other systems.
See, that's the issue, PF and 5e are very different here. If you're not talking about how 5e runs based on running it, you are speculating about how it will run in theory. That's theorycrafting.
Maybe your players are just more retarded than mine, but my players pretty quickly circle the wagons and respond tactically to coup de grace attempts
No, it's that 5e is a different game than Pathfinder. Since it's a different game, there are different consequences to different choices. You can't just assume your Pathfinder experience applies and theorycraft based on it. Here are some very important differences that affect unconsciousness and healing:
- A cleric can heal at range as a "swift action" with a 1st-level spell.
- 5e casting isn't Vancian. A 5th level cleric who prepares Healing Word can cast it up to 9 times per day, so they tend to pop those heals more.
- A coup de grace does not provoke an attack of opportunity
- There is no such thing as a "full round action" that requires sacrificing movement
- Moving next to an enemy is much more permissive; you may move freely as long as you don't leave the enemy's reach.
- A monster can move his full speed and do his full attack.
- There is no way to gain multiple attacks of opportunity, i.e. no Combat Reflexes feat. You get one reaction, full stop.
- 5e clerics can move, heal, and attack in the same round.
- There are no negative HP, so a 1st level spell instantly heals a downed character to consciousness.
- A character who has just been awoken can spring to his feet, move, and make his full attack all in one round.
This is why your intiution about the monster taking a "hail of arrows and axes" doesn't apply to 5e. I'll give a simple, but realistic example. A thought experiment, not meaningless calculations about expected value and DPR.
Consider this layout: A Thug (D3), who has 2 attacks, and a Bandit (E3), who has one, meet your usual Fighter (C2)/Cleric (C4)/Rogue (B4)/Wizard (A3) party, placed as so. Assume there might be more enemies, I only put the two relevant to the example.
In both PF and 5e, the Bandit opens up with a lucky critical hit on the wizard, knocking him unconscious at -8 hp in PF, 0 hp in 5e, but not killing him. It is now the thug's turn.
In 5e, the Thug simply walks up to square B3 and hits the Wizard twice. The wizard is now done, get a new character sheet. In Pathfinder, should he attempt this, he will draw AOs from the Fighter at C2 and the Cleric at C4. He also loses his Full Attack, so he bonks the rogue. He will then endure a full round of attacks, including a Full Attack from the Fighter before attempting his coup de grace. He will then suffer 3 more AoOs before finally striking the wizard.
Notice the difference. In 5e, the Thug endures zero hits to kill the wizard. In Pathfinder, he gets hit up to 9 times before attempting his coup de grace, which will probably kill him first. In PF (and 3.5), it is absolutely not worth it to kill the wizard. Agreed. In 5e? Totally different calculation.
Now, let's suppose the Thug instead decides to ignore the downed wizard and beat on the Fighter instead. In 5e, the Cleric uses Healing Word, then hacks at the Thug with his battleaxe. The Wizard jumps to his feet, casts a spell, and pretty much everyone else gets their shot at the Thug. In Pathfinder, the Cleric has to move to the Wizard to case Cure Light Wounds, drawing an AoO from the Thug. CLW is a Standard Action, so no attack for the Cleric. He rolls 7 hp. The wizard is still unconscious, so only the Rogue and the Fighter get a shot at the Thug. In 5e, he gets attacked by all 4 characters. In Pathfinder, he only got attacked by two.
At least in this scenario, it's a lot smarter for the Thug to keep attacking the front line in Pathfinder, while it's smarter for him to knock out the wizard permanently in 5e. Obviously, the Thug does not sit there with a calculator or a rule guide, and not every situation is the same. But the general principle is that in 5e, delivering a coup de grace is a lot
less risky than in 3.x, while giving the Cleric a chance to heal an unconscious ally is a lot
more risky. The enemies are at least as tactically aware as the players are, and the fact that healers are quite dangerous, while it costs virtually nothing to give an enemy's skull a second whack, is something the sentient ones know.