It’s my understanding that the “at the following oil change” language is in the manual to satisfy CAFE requirements/MPG purposes and not for any other real reason.
The ancient 2.7L engine in my Tacoma originally called for 5W-30 in the US but was back-spec’d to 0W-20 several years ago. I use 5W-30 in it since it is a little quieter/smoother/less clattery with it and because our Yaris takes 5W-30 (I buy the boxes of synthetic Kirkland oil at Costco).
I’ve had the same thought as you to use 0W-30 but haven’t switched since it’s a little pricier. (I use the Costco synthetic oil that is $30.99 for 10 quarts … truck takes about 6 quarts, car takes about 4 - it’s perfect).
Anyway, what I did was to find the Australian owner’s manual (not subject to CAFE) for a vehicle that uses the same engine (in my case, the Hilux) which says that 0W-20 is preferred but that anything up to 10W-30 can be used. Look here: https://toyotamanuals.com.au
Hilux page for the 2.7L
https://i.imgur.com/Mxh4ErX.png
Here is the owner’s manual for a 2016 Australian V6 Highlander (called Kluger down there). They say 5W-30 is the thinnest allowed and that you can use up to 15W-40 (!)
https://i.imgur.com/0CVv9Cl.png
There’s a school of thought that setting the normal oil changes at 10k miles keeps costs low for Toyota during the free ToyotaCare servicing, which lasts for 2 years or 25k miles.
If they required oil changes every 5k (the severe schedule) they would have to do 5 oil changes during ToyotaCare, but now they only have to do two.
Many people have some or all of the aspects of the severe schedule (short trips, city driving, gridlock, towing, off-road, etc) and should be doing oil changes every 5k. Personally I do it every 6 months or 6k± miles (myself, so it only costs about $25 with Costco synthetic).
IMO the 10k oil changes are fine if you plan to keep the car for 5-8 years and sell it before it hits 150,000 miles. But if you plan to keep it for 250k or more, change the oil a little more often.