The big upgrade in USB-C for mobile devices is power delivery; a secondary benefit is video output for laptops, enabling docking using a single cable instead of an old-fashioned dock. PCs aren't in the power delivery game and don't really need an extra video output. Meanwhile, USB 3 over a USB A socket is still able to transfer 500 MB/sec of data - I just did this earlier today, copying from an old M2 SSD in an enclo…
USB C is easier to use. Machines should have more C ports even if they have to share controller lanes--rarely would anyone be in a situation to saturate the system but being able to have multiple devices plugged in at once is useful. I'd be perfectly happy with an internal USB C hub--but I have never seen such a thing. (I *do* have an internal USB 3 hub. Same issue--the convenience of multiple ports, I don't need the…
Not in my experience. The last few times I went to try to use one of my USB-C peripherals it was a pain. For example I wanted to use my portable external monitor with my laptop. Both are "USB-C" however the issue is that USB-C describes the physical connector and not much else. I already new my laptop supported DisplayPort Alt Mode and I knew that was what the display was expecting (rather than being USB display adapter). However, I then ended up digging through the box of USB-C cables testing them until the third cable I tried lit the screen up. This was the general experience with my Thunderbolt M.2 interface as well. I don't have much that takes uses PD but as I understand that's yet another dimension of permutations.
Without intimate knowledge of both devices /and/ the cable it's hard to say what any combination of "USB-C" parts will do. Even OEMs fail to get this right. I friend recently told me of buying Dell laptops which offered a dock as an option. Unfortunately, the dock expected Thunderbolt & DP MST while the laptop only supported USB3.
My personal opinion is that the relative lack of USB-C in a highly competitive, consumer market like DIY Motherboards is likely because even after 10 years the consumer demand is just not there. When judged the more lofty aspirations of USB-C that are being expressed here (replacing most if not all USB-A, HDMI, DP, Thunderbolt, and lower wattage power cables), I consider USB-C to be a failure.