Don't get me wrong: I still think the cartridge format has unique merits, and it's the only way to go on vintage systems. But for modern systems, cartridges would never work, for a variety of reasons.
...Just feel right! Especially if your my age. I love my Harmony and AtariMax, but I still keep my lose cart collection because I also love to swap out carts. It just feels right. Can I get an amen?