I'm struggling to find your logic here.
They don't know what is going on because they failed their Perception check, not because they are being punished for having a feat.
The punishment for the feat isn't the lack of knowledge, it's being forced to act without a reason why.
How is being able to move/act worse than not being able to move/act? The feat makes sure you have the option.
Nothing is wasted by being able to act. Acting first, before there is an enemy in view, does not take anything away from you. You would still act in round two the same way, surprised or not.
Wait, I'm confused. You've stated that if there's a hidden attacker, you force people unaware of the attacker but still able to act to pick an action without knowing anything about why. Let's unpack this, then:
DM says roll initiative. I ask why, the DM says you don't know, but you won initiative, what do you do. I again ask what's going on to cause initiative, and I'm told nothing that I'm aware of, so I can either choose to engage in metagame thinking and pick and action with no in game reason that's defensive, like dodge, or metagame and pretend I don't know anything and blunder on. When the unknown cause of initiative goes, they can now pick an action to take advantage of my chosen action and retain all of the other advantages they had if I had lost initiative, only now I do not get to take a meaningful action in the first round.
Let's say I lose initiative. The bad guy get to do exactly the same thing, but now I get to react with a useful and meaningful action on my turn.
Please, praytell, expound upon how the first is better than the second.
Are you saying that even those PCs who failed to perceive the threat somehow know all about the threat?
Yes, if you call for initiative, there is a threat that is known.
That's your job -- be it a noise, a shout, a sudden movement in the shadows that sets you on edge, something.
By what mechanism are they aware that there is a wizard around the corner speaking verbal components if they failed the roll to determine if they heard the wizard?
Why does the wizard casting a spell start initiative, then? He can't target the players, so timing is unimportant in whether of not he can finish his spell, so there's no need. The wizard casts his spell, some players hear him the others are taken by surprise by the effects when you call for initiative when those effects are noticed.
You're picking the wrong point to enter into initiative.
It does not make sense that those who fail to perceive the enemy know all about the enemy anyway!
Yes, that doesn't make sense, very good. But we're not talking about how perception checks work, we're talking about how initiative works. The failure of the perception check means that a character doesn't know where the threat is, not that there's no threat. If you ask for initiative, it's incumbent upon you to make the threat known. If there are players that are not aware of the threat when initiative starts, that's what surprise is for. If some of those players have the alert feat, then they're not surprised, but still aware of the threat. They may not know where the hidden wizard is (the wizard is hidden, after all), but they should be aware of the threat in some other way. "You have a tingle of danger from your right", "you hear a low chanting as if spellcasting, but can't tell where it's from", "you see a glint in the darkness that warns you of danger", whatever floats your boat. But there should never be a point where you, as DM, have asked for initiative, and a player wins that contest, and you smugly say 'you have no idea anything's wrong, so what do you do knowing nothing is wrong?'
First, the Perception roll determines if they perceive the enemy or not. Because of the feat, they will still be able to act/react whether or not they perceive the enemy.
Second, initiative is not a 'succeed/fail' type roll. It simply establishes your place in the order.
If they don't perceive the wizard, there's no need for initiative. The wizard, hidden, does what he wants. If the wizard starts to attack the party, he's doing something that means he's attacking. If you call for initiative, it's on you to know what that is and relate it.
DM -- "There's a sudden low chanting from the darkness with that feel of magical energies coalescing. Everyone roll perception, DC 14, and then initiative. If you fail the perception check, you're surprised."
Darnell -- "I failed the perception check, but I have the Alert feat. I have a 19 initiative.
DM -- "Okay, you beat the bad guys in initiative. You know there's some casting coming from the north corridor, but you don't know where. What do you do?"
See, you don't have to provide perfect information, but you do need to set the scene so that the players have enough information to make meaningful decisions. As you present it, it goes something like this:
DM -- everyone please roll Perception, DC 14.
Bob -- I got a 12.
DM -- okay, you're surprised, roll initiative.
Bob -- I got a 19 initiative, and I have the Alert feat, so I'm not surprised.
DM -- cool. What do you do?
Bob -- um, what's going on?
DM -- you don't know, it all seems normal, what do you do?
Bob -- uh...
This is unsat.
Rubbish! Just because the combat is about to kick off does not mean that all combatants instantly become aware of all hidden enemies whether or not their Perception checks beat the Stealth checks! This is just absurd!
Aware of danger, not necessarily aware of all things involved in that danger. Enough of a framing to make meaningful decisions, and not like poor Bob above.
