You can change the RPI USB current limit. Keep in mind that the PSU also is able to deliver the current, e.g. 2Amp.
All that max_usb_current=1 does is to set GPIO38 high, which in turn turns on a FET, which connects a second 39K resistor in parallel to an existing one, on pin 5 of U13, the AP2553W6 USB power manager, lifting the current limit from 0.6A to double that (1.2A)
sudo bash cd /sys/class/gpio echo 38 > /sys/class/gpio/export cat /sys/class/gpio/gpio38/value
# gpio -v gpio version: 2.20 Copyright (c) 2012-2014 Gordon Henderson This is free software with ABSOLUTELY NO WARRANTY. For details type: gpio -warranty Raspberry Pi Details: Type: Model B+, Revision: 1.2, Memory: 512MB, Maker: Sony
# gpio -g read 38 1