A real backward step as far as I am concerned, yes I'm sure the reasoning behind it is weight and nothing to do with cost.
I was out with a friend who had just taken delivery of a new car several weeks before, we were traveling on the M6 when his front near side tyre blew while doing about 70 mph in the middle lane. By the time we managed to pull over onto the hard shoulder the tyre was shredded.
The can of sealant was pretty useless, no spare, completely in the hands of the recovery services, not only that but plans for the next day were scuppered as we had to wait why a tyre was sourced and fitted.
With a spare we would have been on our way in 30 mins and the only disruption the following day would have been to drop the damaged tyre off at the local depot.
Shortly after this my daughter purchased a sports car, it was the top of the range model with the larger alloys, all the other cars in the range came with a spare wheel except this one, it had the same well in the boot for a spare wheel but instead had a foam insert with a puncture repair kit.
First thing I did was to buy a Jack, wheel brace and a steel wheel and tyre that gave the same circumference as the original, removed the foam insert and put the wheel and bits in.
Off memory it cost me about £150, it was money well spent and paid for itself more than once.
But I come from the generation that "had" to do all their own maintenance and repairs and a had "Belt and Braces" approach, I'm sure a lot of drivers now wouldn't know what to do with a spare wheel if they had one.