Well here are some excerpts from a fascinating essay in the introduction to Aaron Shearer's "Classic Guitar Technique", 1959:

"The second type of guitar does not have a set describptive name to distinguish it from the classic guitar. It is sometimes called the plectrum guitar, pick-style guitar, American jazz guitar, and the rhythm guitar, although it is not necessarily restricted to playing "rhythm" or strumming. ...
"An oval or triangular shaped plectrum (pick) of tortoise shell or similar material, held between the thumb and index finger of the right hand, is used to sound the strings. Employment of this single device in playing the plectrum guitar sets serious limitations upon the instument...Melody with the supporting harmony necessary to give fullness and color to a composition can be produced in only a limited sense when the guitar is played with a plectrum. As a matter of fact, the harmonic combinations and range of tone necessary to the solo performance of fine concert music simply are not available on the plectrum guitar. ...
"The plectrum guitar is excellent as a "rhythm" instrument, working, as is customary, with bass and drums to set the beat of the modern studio or dance orchestra. (In this tyhpe of accompaniment the correct resolution of chord tones is relatively unimportant.) It produces a brilliant, rather metallic tone, which in addition to being suitable for "rhythm section" work, is also used by "western style" and "hillbilly" singers in playing simple accompaniments. When amplified electronically (it is then called the electric guitar), it is most effective as a "melody" instrument, usually playing a single note at a time, but ocasionally brief chord passages. The electric type of plectrum guitar is widely used as a medium for playing various types of modern jazz, popular music and "western style" music. ...
"For beginning students the classic guitar is unquestionably more rewarding and actually easier to play. As will be noted in this book, surprisingly melodic and full sounding little solos may be played after only a few hours of good study. the reason for this is recognized in the fact that the classic guitar, played with the thumb and fingers of the right hand, permits the execution of widely spaced harmonies of two or more notes simultaneously. It is easier to play simply because the strings of the classic guitar are softer and more flexible than are steel strings, resulting in less irritation to the left finger tips.
"Which instrument is more difficult to play is a relatively unimportant question, however; the first consideration for the student is which type of guitar will bring the most personal stisfaction and will more fully satisfy the individual's taste."

So there you have it. From a classical guitar teacher, of course! I think a few things have changed since then...amazing that this was written as late as 1959.

Aloha,
Mark