I have wondered for a while what the purpose of Cut Time (2/2) actual is. While studying music theory I've always been told the reason is to reduce the use of eighth notes and sixteenth notes in a piece, but to me it would seem that there are better ways to accomplish that. It also seems that because the half note gets 1 beat and only two make up a measure it will just feel like a different type of 4/4.
Does anyone have a good explanation of what the purpose of Cut Time is?
The purpose of "Cut Time" is not to reduce the use of eighth notes and sixteenth notes in a piece, it is to facilitate easier reading for musicians. Simple metric durations (e.g. 1-4) are much easier to calculate and respond to than, let's say, 32nd notes, which take just a moment longer to interpret because of the additional visual stimulus.
When a player is playing at a quick tempo, they use more of their resources (mental capacity) to concentrate on the external factors (getting all the notes in, staying up to tempo, etc.) To compensate for this, composers should provide less visual stimulus to help the player. The converse may be stated for slow tempi, but again, some composers take it a little far. But I digress.
As noted in the question, one possible solution would be to merely change the tempo marking. Though it is a logical solution, it is rarely a practical one. Technically speaking if the tempo were increased to 212bpm in 4/4 time, the conductor would be left to try and execute a very quick 4/4 pattern, which no conductor would do.
At a certain point, beats per minute fall into larger subdivisions known as hypermeter. A silly tempo marking of 300bpm could easily be re-written (and felt) at 150bpm.
In some instances (such as a march!) Cut Time also helps to illustrate phrasing more clearly than it would if the piece were in 4/4. Cut Time allows composers, performers, and conductors to "zoom out" a little bit from the score / music and get a better sense of the larger picture.
