I used unbranded Epson-compatible carts in my old 640 for several months. They worked fine, but the colour purity wasn't quite the same. The hues always came out a little warmer than they were supposed to. Also, the newer Epsons use enhanced 'light fast' inks, which when used with the right...
I think the reason Epson designed it that way is to stop the clogging of the ink channel into the head. If you've been using a cartridge, there is always a little bit of ink left at the top of the head when you remove it. If this is left open the ink will eventually dry. By forcing you to...