I would think that the AC conundrum is exactly why they have Defender HP despite being Strikers.
But if they're balanced with low dex/int and light armour, what happens when they ineviatbly pick Chain proficiency?
Then you've identified a potential problem with the class. =)
I doubt anyone envisions barbarians in full plates when they think of the class, so this is probably something that should be brought to the attention of the designers as a potential flaw (if they're not aware of it already).
I'd say the warlock is in worse shape, and it's not just limited to star pact either. True, the warlock has ranged attacks, but they're very short range; he's not sniping from a clock tower or anything. It's short enough that enemies can close the distance to melee if they desire, and that's to say nothing of the fact that (contrary to the bizarre notion I've encountered often) quite a few monsters are actually quite capable of attacking from range themselves. In general, monsters can pull off a lot of the same maneuvers that PC's can, so if they're consistently pancaking against the party's front line, then that's just that particular DM allowing things to happen that way by not using skirmishers, lurkers, and artillery monsters to good effect.As Star Pact warlocks, yes.
Its a little worse for the barbarian, because that Con modifier shows up absolutely everywhere in the powers and class bonuses previewed. But its basically the same boat. ...but its also a little easier for the barbarian, because pumping con will let them easily meet the chainmail armor prereqs, while the star pact warlock has to put some points into Str to get that. ...but the star pact warlock is a ranged combatant, and the barbarian is melee. ...but the barbarian has all those (con-keyed) abilities that give him temporary hit points.
So... different boats, same river?
See above. Apparently, it must be balanced since the 'lock, whose limited to leather, is stuck with the same HP as a rogue.This.
If they have the same AC as other strikers then they would most likely have the same hit points as other strikers, otherwise they'll be overpowered.
Their defense is hit points.
I don't think it would sit well with anyone if the Barbarian has the same hit points as a Rogue, so we're stuck with lower AC.