small hands should be fine too
I assume the back buttons also work as shoulder buttons (or can be configured as such), meaning you can turn your hands even more.
(EDIT: disregard the chinese, just picked the first video that wasn't an obvious shill with with millions of views).
the thing is you want A, someone wants B, someone else C, and you can't satisfy everyone without the cost going through the roof. every feature has a cost/benefit, that's just the way it is.
as for the touchpad, that's for mouse emulation for games that don't have controller support. remember the steam deck is also supposed to run other games than the console centric ones or ones that haven't been adapted to controller input yet (like I said before it's the same reason the steam controller had them, if you wanted simple dual stick inputs there already were plenty of other controllers available). don't think they will be that hard to get used to, the tiny af buttons on non-adapted pc interfaces will probably the biggest pain.