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.
Except that the system incentivizes the "slogging through encounter after encounter without rest" model, through its "milestones" system,
where you get benefits for going through two or more encounters without rest.
And as for your second point, dwarves can use their second wind action as a minor action. That's the same required to use a potion, so after their healing
surge value exceeds 10 hp, they have no reason to use a potion of healing.
Edit: And both the Paladin's and the Cleric's basic "per encounter" healing powers are also minor actions.
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.
Except that the system incentivizes the "slogging through encounter after encounter without rest" model, through its "milestones" system,
where you get benefits for going through two or more encounters without rest.
And as for your second point, dwarves can use their second wind action as a minor action. That's the same required to use a potion, so after their healing
surge value exceeds 10 hp, they have no reason to use a potion of healing.
Edit: And both the Paladin's and the Cleric's basic "per encounter" healing powers are also minor actions.