7) Python is designed to be written more like English than other programming languages.  English is written horizontally, not vertically.  In furtherance to an attempt to make "readability" an objective argument, here is a scientific study which finds that greater character width lines improve readability:  http://psychology.wichita.edu/surl/usabilitynews/72/LineLength.asp.

To summarize, the study found that of the choices of 35, 55, 75 and 95 character lengths, 95 was able to be read the fastest.  Please note that they did not try 115, 135, etc. and that they found their maximum data point at the farthest edge of their study.  One can conclude that they probably should have gone even further to determine where (if ever) it tapers off.  This study focuses on reading English, not on reading code.  But given the first sentence of this point, it should at least loosely correlate.  At any rate, it's an attempt at something scientific on the issue.