You’re not alone. Ever since the redesigned iPads came out 4 years ago I’ve periodically placed a cellular iPP 12.9 with 512GB in a cart along with all the accessories I’d need and looked at the price only to say $%# no. At some point soon probably, iOS will make the 2017 iPP’s obsolete but until then I just can’t stomach the cost to upgrade despite having the disposable income to afford it.
Some of OP’s wishlist items would only lead to even higher prices, and I just can’t see how that would be worth it without some major improvements in iPadOS.
I've had 3 years to get used to the new pricing. The 2018 iPP 1TB LTE was $1899 at launch vs 2021 iPP 1TB 5G $1999 so pretty much around the same price.
At least for my usage, the 2021 iPP is a worthwhile upgrade over the 2017 iPP. Multitasking and multiple Safari tabs was getting problematic on 4GB RAM after updating to iOS 13, and iOS 15 has even worse memory management. The 2021 iPP hardware has a lot of breathing room so I think I might even end up keeping the M1 iPP as long as my Windows laptops.
My mom is happily using my old 2017 iPP for Netflix, Amazon Prime, HBO Max and Disney+.