But now we lost one TB3 port for a HDMI port that most will never use or at best use infrequently.
Ah, yes, the mythical "stolen TB3 port"...
Each TB/USB4 port on the new M1 machines now has its own, dedicated controller on the SoC, c.f. the old intel machines where each pair of ports shared the bandwidth of a single controller. So the M1 Pro/Max machines actually have 50% more Thunderbolt bandwidth than the old 4-port Intel MBPs, and the ports now support the new TB4 hubs, so each of those 3 ports can now run a hub with
4 TB4 ports that can be used for TB/USB or DisplayPort.
...according to Apple, the M1 Pro/Max chips have 3 Thunderbolt controllers. There's no evidence of a 4th TB controller that has been stolen by the restored ports. The SD slot just needs a USB 3.0, HDMI just needs a spare eDP 1.2 stream, and the MagSafe doesn't need any CPU resources whatsoever (maybe a USB 2or IIC or suchlike for control). An extra
full function TB4 port needs a huge amount of resources in comparison.
Also: take an old 4-port Intel MBP, connect a charger, plug into a data projector or TV (a pretty common scenario) and count how many TB ports you have free for other things -
2. Now do the same with the new M1 Pro Macs - the charger goes into MagSafe, the TV goes into HDMI
and you still have all 3 TB ports left. Yes - you
could carry a multiport dongle, but now you don't need to - and if you
are prepared to carry a hub around you can now use a TB4 hub that gives you 4 extra TB ports, a bunch of USB 3 and still leaves two of the original built-in TB ports free.
This is the problem with the whole USB-C concept: one port for all sounds cool, but it actually means funnelling several scarce but unrelated resources: PCIe/USB3, video streams and power input/output - through a single connector and creating an artificial bottleneck. Plug a charger in and you can't use that port for data or video, plug a display adapter in and you can't use it for video and data.
It would be fine if you could have 6-8 of those universal ports in those machine so there were plenty of holes to go around - but that's far more expensive and complex than adding dedicated ports for the most common requirements. Or it's fine if you are going to carry around multi-port hubs - but that's a disadvantage for an ultra-portable laptop.
The HDMI and SD slots aren't there for your super HDR 6k display or the CF super-express-plus-bingo camera body you're going to buy in 2 years' time - they're for boring but common scenarios, like when you want to want to plug into a data projector at a meeting or a hotel room TV, or offload photos from your camera or drone to free up space in a muddy field and it's really, really convenient not to need an adapter.
What the new MBPs have done is to give you fewer, higher bandwidth bandwidth "universal" ports that can be used with hubs, docks & daisy chains to efficiently drive multiple devices, plus a reasonable selection of single-use ports so you don't have to waste the universal ports on
single use devices.
It's a pity they couldn't have stretched to HDMI 2.1 and/or squeezed in an extra USB-only port, but bandwidth doesn't grow on trees, and maybe they
would have had to steal from TB (particularly for the HDMI 2.1).