You can charge with both, in any port (I have a Macbook pro with Magsafe, but primarily use all the USB-C chargers I have lying around)
You can charge with both on the 14" and 16", at the apple store a few weeks ago they told me the next one's will likely have the same capabilities.
That's awesome, thought they were doing a 180 and forcing magsafe charging only.
Why is that a downside? Magsafe was one of the best things about the older, early-2010's Macbooks.
I for one love charging with USB-C. By now I have USB-C cables laying around a few different places in the house, and can charge almost anything at any one of them. No going to the other room to get the cable.
Magsafe is fine; having to travel with a separate charging block is terrible. The USB-C consolidation has been awesome for people like me who travel frequently- my phone, external battery, M1 Air, headphones, Nintendo Switch... all charge over USB-C, so I only have to travel with a single charger. It's wonderful
The new MagSafe doesn't have a captive cable on the charger. It is a MagSafe cable plugged into a USB C charger. You can charge via a USB C cable but you give up a port and you can't get quick charging.
The USB-C port is also awesome for docking station setups. Just one cable to plug in for power and all peripherals. But for mobile use I definitely like to have the choice of magsafe.