The problem that many have with port compatibility. I love Thunderbolt 3, and personal setups can be changed or adapted, but that doesn't work for everybody. Some people have to adapt to older standards and they shouldn't have to carry around adapters for their portable computer.
And you don't have to carry around adapters - there is a native USB-C cable for every USB connection available. Just upgrade the cable - and yes thats upgrade because now instead of having a clunky type A to plug into your computer, you have a small type-C which can be plugged in, in either direction. If someone had given me the choice of buying those cables 15 years ago when type-A came out id have done it in a heart beat, now you can, people actually complain?? It's mental.