Sorry to dredge up an old one, but there seems to be a lot of speculation here that facts can fix.
The 44 RF was designed in the late 50s to 1860, as it was the cartridge for the Henry (1860). Remember that metal fabrication and materials were rudimentary, and a folded-head rim-fire case was but one of many weak cartridge designs. The fact is the 22 and 44 RFs were the cheapest, easiest to make, reliable, and good-obturating designs of the time. But the early copper cases (and the thin-ness required by their folded-head design) made them poor pressure vessels, and hence more inclination towards light loads (though, as pointed out, incrementally stronger than the rocket balls of the volcanic).
The other aspect is this incremental improvement. Technologically, it's quite rare to have a major leap forward that skips steps. Guns are no different. The switch over from flintlock to percussion happened fairly quick, but the change from smoothbore muskets to rifled rifles happened slower, and we can find all four permutations of these combinations in different countries/armies, especially in the 25 years before the US Civil War. Self-contained ammunition is no different. The Rocket-Ball was the beginning of the concept from a muzzle-loading point of view. Then someone said, let's stick a percussion cap under the ball, and the 22 RF was born. Then someone combined the rocket ball and 22RF and we got the 44 RF, but they also wanted more power. With the restrictions of the types of cases involved as I described above, they avoided going too far (which is unsafe from a business point of view too - if it fails, you might go under for wasting too much capitol on a bad/non-recoverable/non-saleable idea), so you get the "weak" 44RF.
To the folks in the 1860s and 70s who chose/preferred Henrys and 66s, 16 quick shots with quick reloading was a fair trade-off compared to having one shot that was more powerful.
As to the original poster's question, I think we must remember that looking backwards from an era where we have 460 S&W and 500 S&W Magnums (or even just looking at the most popular magnum pistol, the 44 Mag.) or the 30-06, 338 Magnum, etc., yes, the 44 RF looked pathetically anemic. It was, after all, designed and produced as a rifle round first and a pistol round secondarily (because Colt and S&W could see the market 10 years after the 44RF first emerged). But let's look at it another way --
Not many in the personal defense field today snicker at or deride the 45ACP as a good cartridge. Stick it in an SMG like a Thompson, and most people think the 45 is quite impressive as an offensive weapon... Well, taking into consideration bore diameter, velocity, bullet weight, and rapidity of fire and reloading, it's not a far stretch to think of the 1860/1866 as the Thompson SMG of the old west. That's the perspective I think one should take when looking at these rifles, because to the folks back then coming out of the muzzle-loading era, it's a similar technological advance. Makes one feel a lot better about the 44 RF, doesn't it?
In a similar vein, the Trapdoor Springfield could be looked at as the M-1 Garand of the old west (because the Trapdoors reload-ability was that much of an improvement over muzzleloaders, it's similar in tactical improvement to the self-loading Garand over a bolt-action). And, just as our military had Garands and Thompsons in WWII, for slightly different expected tactical needs of combat, the old west had single shots and repeaters, and which one you wanted depended on your beliefs/expectations of your tactical needs (taking away the two most common limitations on this choice - your finances and availability of the weapon).
So, if you'd respect the idea of the 45ACP or maybe the 40S&W as a "powerful" or effective cartridge today, I suggest you view the 44RF in an identical frame of reference.