I think Agamon has the right idea of it here. In any edition of D&D, an on-level encounter designed for a party with 4-5 members has the potential to steamroll a party with 2 members. WotC certainly could have done a better job advising DMs on rebalancing the encounters for a small party, but if you have experience DMing prior editions, you should probably realize that something needed to be rebalanced.Two players? Did they have 2 PCs each? Was the encounter balanced for two PCs if not? Even that is a struggle, as less PCs means more swinginess.
I've had a death and a near death in my four sessions of 5e I've run, but nothing near a TPK, especially before anyone can act.
Now, your point is taken - if monsters win surprise and focus their fire, they have the potential to take down a PC or two before those characters get to act (especially squishy wizards, etc.). However, with a properly sized party, the other characters ought to be able to use their actions to win the encounter - if a cleric is still standing (the pregen seems quite likely, with an 18 AC and 11 HP), then the downed characters can be healed and back in the fight. If not, then they could target a few goblins to reduce damage taken (most attacks my players made took the goblins out in one shot), then make healing checks to stabilize their fallen friends.
Sidonunspa, I don't think your numbers are quite right. Using the pregens, the highest Passive Perception is 13, and the goblins have a Stealth of +6 (so surprise is fairly likely). They also have +4 to hit and deal 5 damage on average, so it's totally possible that the four focus firing goblins could drop the squishier PCs (Rogue and Wizard) with a few good rolls. I think the real problem is that it sounds like the fallen PCs had no friends around to help them - once you have a friend stabilizing you, death rolls are much harder to fail.Heck I just played last night....
your party must have had a run of horrid luck...
So ren1999, I'd encourage you not to give up on D&D 5E just yet. I think the real culprit wasn't low starting HP, but improper encounter balance, which could have been avoided. According to Mike Mearls' article this week, an encounter of four goblins (50 XP each, x1.5 for outnumbering 2-1) against two level 1 PCs is rated as "Hard," which I think in this context means "risk of PC death," where the original encounter was rated as "Average" for four PCs. If you wanted an "Average" encounter for two level 1 PCs, you would want to pit them against two goblins. Unfortunately, the rest of the adventure would need to be rebalanced the same way, but by using the table it shouldn't be too hard to find appropriate monsters. (Also, keep in mind that an adventure for any other edition would need to be rebalanced the same way for a party half the correct size).
Have a good day!