Maybe they are now, but back when my kids were small and pumpkins had just started to arrive here I wasn't impressed with the flavour, but pumpkins look smaller now and are maybe a better flavour. If I was to do it now I'd probably go for one of the better cooking ones that supermarkets sell beside the butternut, dearer but probably nicer. I hate waste though and would probably use the flesh, but I would add butternut to it as well, oh and lots and lots of spices and seasoning!
I having been making pumpkin soup for 15 years multipoodles and never had a problem with the flavour. I just use stock,onion and pumpkin and sometimes a bit of garlic. Although there is a very nice recipe on the bbc website with coconut cream and thai curry.
I thought that our pumkins were grown for animals rather than for humans and as such weren't really designed for us to eat. Similarly the ones in the shops have "carving pumkins" all over to make it clear they aren't designed for eating! I know I had a US friend that used to moan about this.
However if people are making it work it seems a good idea. It would be such a waste.