We all have our opinions on the original brakes. Diggers opinion differs from that of Bruce W. which differs from mine.
All I will say on this is that IME, done right, the original brakes will skid all four tires on blacktop. I know of at least seven Jeeps with original brakes that will skid all four tires. What more can one ask?
I suspect that many folks are used to modern disc brakes. I also suspect that drum brakes are a tad out of their experiences. Thus, they think that the original drum brakes are no good even when they are fine.
From my perspective & IMHO, if I were faced with an original brake system needing "rebuilt", or replaced, I would go with either late model 11" drum brakes, or convert to disk brakes. Cost wise, in both time & money, either "upgrade" might actually be cheaper than replacing all of the original components with new original ones. Another plus to these upgrades is parts availability. So far, I can buy parts for my 11" drum brakes from NAPA. If I went with discs, I would make sure that the cylinders, discs, & pads are readily available before I purchased, or made an adapter kit.