The 9.7 pro was not 50% more expensive but 20% more, with double the initial storage ($599 vs $499 at launch). Sure if you thought it was 50% more expensive that's a totally different value proposition....
The 10.5, which added another $50 to the price, was good value only for those who didn't have the widespread white spot issue....
I have had the air 1, air 2, 9.7 pro, 10.5 pro and 11 pro, as well as the mini 2, 4 and 5. If I could go back in time in hindsight I would skip the air 1 and 2 entirely (and only get the mini 2), then get the 9.7 pro, which is still much more functional than the air 2 (for the reason I mentioned), would totally skip the 10.5 (for me the worst pro ever after the white spot) and would get the 11 pro, which while $150 more expensive than the 10.5 was a much bigger jump than the 10.5 was over the 9.7 and it's still an amazing device today, so much that I have not considered the 2020 or M1 (I would also, in hindsight, skip the mini 4, which is a slightly downgraded air 2, and wait for the mini 5, which is light years ahead of the 4)
Having said this, giving 2GB RAM, probably to hit the $599 price point, was a mistake by Apple, they could have increased the price to $649 and give it RAM parity with the first pro, making it much more relevant today, just like (or even more than) the bigger brother....