Non-replaceable battery is probably a primary why this may not be the case. My iPad 3 seems to be discharging much more quickly these days, and will probably mean a replacement will be needed sometime next year.
But those issues are sort of cheating since they are basically planned obsolescence features that could trivially be solved if there were any incentive to do so. But there isn't, so more landfill generated for little actual new value.
I'm going to guess you're neither a computer hardware nor a battery engineer.
See: Teslas, which have to live by the same rules as everyone else when it comes to battery life issues but whose solution isn't 'throw your car out when it won't hold a charge anymore'.
When Teslas have seen the kind of prolonged use and abuse people's phones and computers have taken, let's see how their battery packs do.
And of course, Apple sells battery replacements at pretty reasonable prices, but most people don't bother because depreciation makes it not worthwhile.
Our kids are using our original iPad 1s and abuse the heck out of them, and they still get decent battery life.
battery as you said is almost the norm now.
sd card dissapeared from all android devices save from some expensive sony ones. and with storage prices dropping (ssd just broke the 50c/gb barries) this is a sure way of making next year device much more appealing.
scren resolution being improved in homeopatic doses. year over year. this also contributes to new storage needs as apps space quadriplicate to support all screen sizes, reinforcing point above.