Unfortunately Epson (and others) build it into the hardware that all cartridges must be above a certain level to print and print drivers and settings usually cannot override this. Epson have a habit now of insisting on genuine cartridges. Refills are okay if they are reset, compatibles often don't work (I had one model refuse to print unless at least one genuine cartridge was in the machine).
Also the 'black only' print setting option in many models just means "print in shades of grey", but that doesn't mean only using the black ink cartridge. Not all models are like that though. The cheaper models tend to be most forceful in ensuring you have all cartridges full and all are used up in equal amounts. Remember that cartridges subsidise the printer price.