In MATLAB, I am establishing a serial link to an Arduino. Is a higher baud rate always better? I am using 9,600 baud now, but that is merely because it is the most standard value.
You'll have better luck over at https://arduino.stackexchange.com/.
Why do people settle?
People settle because it is more than fast enough. The most common use is just to print some stuff on a terminal for debuggin. 9600 baud is 960 characters per second, or 12 x 80 character lines per second. How fast can you read? :)
If your program is using the serial port for bulk data transfer, you would choose not to settle.
See the following resources: