Actually, the B450 Tomahawk, Tomahawk max and Gaming Pro carbon are some of the best boards you can get VRM-wise for Ryzen, at all. Yes, there are some that are better, but they are also twice the price, at least. And there are SOME that are twice the price, and are worse than those boards. Those boards are good enough that I've caved on my long time belief (Still applies in many situations and for many boards though, just not these) that MSI has troubles with quality controls or just quality in general on their budget to mid grade boards. They've always had decent quality on their high end boards, for the last five years or so anyhow, but prior to that there were ample examples of why to not buy an MSI motherboard throughout their product stack.
This platform however, those three boards are very hard to beat, especially considering they are so much less expensive AND there is supposed to be a B450 Gaming Pro Carbon Wifi motherboard coming out soon that has higher speed memory support and supports Ryzen 3000 series out of the box with no BIOS update needed. Not sure when we'll see those, because without the Covid-19 situation we'd probably have already seen them since they were announced several weeks ago.
As I have said before, if you need dual M.2 NMVE drives, you don't want the Tomahawk. It has a single M.2 slot. The gaming pro carbon has multiple M.2 slots which is a desirable feature set for anybody that will be inclined to use multiple NVME drives. At some point you almost have to say, ok, let's just do all NVME drives where possible, because the prices are getting down to where there is some parity and since they are much faster in SOME scenarios, why not.
But certainly standard SATA SSDs are still perfectly fine for the majority of users. I still have some rather large HDDs in my NAS box and a couple of external HDDs as well, although everything IN my machine itself is some kind of SSD.
As to the PCIe 4.0 as mentioned, there is very little, if anything, to be gained in the here and now from using it. If the X570 boards were on par with the quality, performance and price of at least X470 or comparably performing B450 options, it would be different. But they are not. And I seriously dislike the need to run an additional chipset fan, which is a requirement on X570. I'm interested to see what, exactly, the B550 boards bring to the table and what they don't, but I see almost no reason at all right now to go with X570. I've looked at a lot of storage device reviews and to be honest there is very little argument to be made for any benefit even with PCIe 4.0 M.2 drives, for paying the additional expense on X570 just to have it. Mostly it is synthetic in nature and is not anything that any person would EVER appreciate in the real world when it comes to a translation into performance while actually DOING things. Like gaming. Or other common tasks.