In my opinion, and this is from experience, cars should have both sockets.
For instance, if you look at the Leaf 40/62's charging sockets, you have Chademo and type 2. How hard can it be to fit a CCS combo instead of a type 2?
Going through France with the Leaf 24, most chargers installed at Auchan and Ikea only have Chademo and type 2. You also have access to Chademo at Nissan dealerships, where fitted and accessible.
I have seen a single fast charger offered by a French county, a new install, where the Chademo cable is not working and the CCS is.
I remember this one because it was a PITA in an area with scarce fast chargers
https://fr.chargemap.com/parking-covoiturage-3.html
The big problem is, being practically one of very few CCS in the area, you're going to have to wait your turn.
So I can assure you that in France, and that is a big country in the middle of everything, Chademo is a bigger asset than CCS.
In Switzerland, I have noticed that the company Move Mobility is putting DC chargers on practically every highway parking area . I think that most of them are CCS only.
But it doesn't really matter, because you can find Chademo's all over Switzerland offered by Swisscharge, most of them off-highway, but also on-highway where it matters, like the Gottard Sud parking area. Switzerland is not a very big country, so even for a Leaf 24, you don't need more than 3 charges to cross it entirely, and there are plenty of Lidl's offering free charging.
In Belgium, most have both, so it's irrelevant.
In my opinion, it's not smart to standardise on CCS for the companies offering fast charging.
You invest 10+k Euro's on a fast charger, and then you're going to cheap out on a 500 Euro cable (wholesale) and plug to slash your customer base in half... that's the most stupid thing I've ever heard.
So IMO cars should have both and chargers should too.
IMO it's also ok if they use thinner cables for the Chademo and limit it to 50kw.
Also, with bidirectional chargers starting to be offered, Chademo offers some advantages.
Wallbox is offering the Quasar
https://wallbox.com/en_catalog/quasar-dc-charger
Indra is offering this
V2G Charger | Home Vehicle-to-Grid Charger | Indra
Delta V2X
Bi-Directional EV Charger
People don't understand the use for these yet. But countries are moving agressively towards self-consumption and self-storage of solar energy.
In Belgium, the government has just abolished net metering (ie bidirectional electricty meters for homes with solar). This is going to happen everywhere.
People now have to purchase home batteries and a basic 13.4kWh Tesla Powerwall 2 setup is 10k euro's at least.
For 6k you can find a Leaf with 15kWh of capacity, but regardless if you happen to own any EV, you would want it to be able to power your home at night.
Nissan announced the Ariya with CCS, but at the price point of the Ariya, why should the customer have to live with their choices?
I don't think that a customer in France will be happy with CCS.
If you don't offer both, give the customer the choice.
As for Tesla, while they are selling the most vehicles in Europe currently, they would certainly want CCS to move forward so they can sell more Powerwalls.
But their opinion doesn't matter, because most Tesla users will fast-charge at a Superchargers 90% of the time.
So IMO the likes of Ionity and Move Mobility are the ones shooting themselves in the face with CCS-only chargers.