First point: most days, you won't use all of your healing surges. If you are slogging through encounter after encounter without rest, or if you are taking
huge amounts of damage and have healing support, you might find yourself running low, but a healing surge gives you back 1/4th of your hit points. even a
wizard gets 6+con mod healing surges every day, and with fort saves like they are, he's not likely to take his con mod negative - and without items or a
friendly buff class character, you've generally got in-combat use of one of those per encounter. Admittedly, there may be campaigns where the GM rides you
close enough to the edge that you *do* use up all of your healing surges every day, and collapse thankfully into the "sleep for full heal" rule every
night, and in those, healing potions would be largely useless, but most campaigns will not likely be that way.
Second point: The vast majority of ways to use healing surges require someone's standard action. Taking your second wind, having the priest/warlord heal
you, having a friend use the healing skill on you - all of them require that someone take the time out of their day to heal you. In the serious, climactic
battles, every round not spent whaling on the big guy is that much more breathing room for the bug guy to whale on you. Even more, again, you get one second
wind per fight, which means that once you use that, it requires the standard action of a healing character - and if you've got one priest, and two
characters severely wounded....
The healing potion is not what it was. It's not a strategic reserve, for days when the priest is running low on healing (or unconscious, or lost) because,
for the most part, HP are not a strategic resource in 4th ed. When you're in a situation where hp are a strategic resource (encounter after encounter,
when you cannot afford to rest very long in between), they're a generally poor choice - contrast with 3rd ed, where that was the time they were most
precious. On the other hand, it is a tactical reserve - it lets you cram more of your strategic healing resource (healing surges) into your system at a lower
tactical price (minor action and does not expend your second wind.) Much like 4th ed itself - It's nothing like what it once was - but that doesn't
mean that it's useless or bad.
--Edit: though... I do have to acknowledge that Epsilon's response has significantly more win than my own.
huge amounts of damage and have healing support, you might find yourself running low, but a healing surge gives you back 1/4th of your hit points. even a
wizard gets 6+con mod healing surges every day, and with fort saves like they are, he's not likely to take his con mod negative - and without items or a
friendly buff class character, you've generally got in-combat use of one of those per encounter. Admittedly, there may be campaigns where the GM rides you
close enough to the edge that you *do* use up all of your healing surges every day, and collapse thankfully into the "sleep for full heal" rule every
night, and in those, healing potions would be largely useless, but most campaigns will not likely be that way.
Second point: The vast majority of ways to use healing surges require someone's standard action. Taking your second wind, having the priest/warlord heal
you, having a friend use the healing skill on you - all of them require that someone take the time out of their day to heal you. In the serious, climactic
battles, every round not spent whaling on the big guy is that much more breathing room for the bug guy to whale on you. Even more, again, you get one second
wind per fight, which means that once you use that, it requires the standard action of a healing character - and if you've got one priest, and two
characters severely wounded....
The healing potion is not what it was. It's not a strategic reserve, for days when the priest is running low on healing (or unconscious, or lost) because,
for the most part, HP are not a strategic resource in 4th ed. When you're in a situation where hp are a strategic resource (encounter after encounter,
when you cannot afford to rest very long in between), they're a generally poor choice - contrast with 3rd ed, where that was the time they were most
precious. On the other hand, it is a tactical reserve - it lets you cram more of your strategic healing resource (healing surges) into your system at a lower
tactical price (minor action and does not expend your second wind.) Much like 4th ed itself - It's nothing like what it once was - but that doesn't
mean that it's useless or bad.
--Edit: though... I do have to acknowledge that Epsilon's response has significantly more win than my own.