The weird thing about healing potions, in all editions, is that they are more effective the fewer hit points you have.
In 4e, a wizard with 10 Con will have 20 hp; while a fighter with 10 Con will have 25 hp. So the heroic tier healing potion that heals 10 hp can heal 50% of the wizard's hp but only 40% of the fighter's hp.
Healing surges, by contrast, are always equal to 1/4 your hp, so they scale with level, and they also scale with hit points. Does that make any sense? In the same wizard and fighter example, the wizard's healing surge will heal 5 hp, or 25% of his max, while the fighter's healing surge will heal 6 hp, or (almost) 25% of his max.
(Yes, the math is a bit off because of rounding. You get the point.)
If we look at higher level versions of the wizard and fighter, say that eventually the wizard has 30 hp and the fighter has 60 hp. The 10-point potion heals 33% of the wizard's hp but only 16.6% of the fighter's hp. It's still a good deal for the wizard -- better than a surge -- but it's not a very good deal for the fighter. (Obviously, healing is never
useless, but its value relative to the opportunity cost of using it (i.e., the action(s) it takes to use it) goes down.)
Now, as Plane Sailing pointed out, there are paragon and epic tier versions of healing potions too, so you don't end up with something riduculous like the 150 hp fighter still chugging 10 hp healing potions (when his surge value is 37!).
I wonder if the game would still be balanced if healing potions said:
When you use this item, heal hit points as if you had spent a healing surge.
Would that make them too good? they would basically be extra surges per day. They would always heal 25% of your max hp, but they would never cost you an actual surge.
That way if a fighter picks up a potion and drinks it, it is exactly as effective (relative to his max hp) as if a wizard picks up a potion and drinks it. This gets around some weird situations like, "No, Tordek, don't drink that potion -- give it to Mialee; she'll get more use out of it." Shouldn't the magic of the potion work just as well for either character?
I know, I know; hp are just an abstraction, and it's just a game. But I wonder if the "healing potion = free extra healing surge" was tried and found lacking in some way.