I never got why Gibson used smaller frets on the Customs, not that i would buy one anyway but i'd rather get a standard with traditional frets.
Back in the day, 1960, the Les Paul Custom was a really great solidbody option for jazz guitar, ala Les Paul himself. For fast runs and quick chord comping the small frets are really great. While Les Paul could bend notes as well as anybody alive, he chose to utilize a style of playing quick runs and no bending. The small frets facilitate that much better. It's kind of hard to use those fast runs and comp chords quickly and do so comfortably with higher frets so the fretless wonder wasn't all that bad of a design.
Now take a look at some more modern Les Paul Customs and the dominance of rock influenced players who will most likely buy the model, and you will see bigger frets. If you do get a chance to play an original, jazz era fretless wonder you will see and feel the difference.
Fender guitars like my older ones have long been criticized for two things all the time:
1) frets are too small and not comfortable bending
2) trem goes out of tune too much on strat
So when the cleverly designed American Standard strat and teles came out, Fender saw to it that the frets were very large and competed with the popular Jackson and Ibanez superstrats for ease of bending. To address the trem issue, Fender made it float better and be hinged on two screws instead of six which tended to work against itself and destabalize tuning. And besides the sometimes tinny and underpowered attack of old Fenders, the American Standard put in almost humbucker sounding, fat single coils to work distortion a lot better. The mids and lows were pronounced and there was a new growl to Fender guitars not seen before.
The old Les Paul Standards of '58-'60 have much better big frets than any of the then top of the line 1960 Les Paul fretless wonder Black Beauties. And in 1960, Gibson made the neck much slimmer and the combination of that and the frets were an early attempt at what would become the slim neck, fat fretted Wizard necks found and perfected in Ibanezes. But Gibson was the first to try that combo though to a much lesser degree. But pick up a 1958 Les Paul, or reissue, and then play the 1960 sunburst and you will see a guitar model evolved into a much faster machine if taking modern metal into consideration. Add to that a Gibson custom shop Axcess rounded heel neck and satin finish on back of neck, and overwound modern humbuckers in let's say Gibson Dirty Fingers, and you have a really good metal guitar that could handle almost anything thrown at it today.