There are plenty of things in Dorico that can be done in multiple ways: pretty much anything can be created by clicking and dropping from the left/right panel into the score, but keyboard shortcuts and popovers tend to become quicker.
I suspect most people who’ve chipped into this thread so far live mostly with notation, as opposed to piano roll. For those of us switching from e.g. Sibelius, it’s revelatory enough to not have to think about how a tied note is grouped. Not actually having to think about how long the note is goes one step further. Even after three years of using Dorico daily, I sometimes still have to force myself to type note values that don’t correspond with the tie chains that make it onto the page. In regard to any of the examples you’ve given, I wouldn’t be resorting to the Alt+Shift+Arrow command; I’d be asking myself how long the note needs to be, typing that note value and then pitching the note. It’s just how my brain works.
My guess is that if I mostly lived in Cubase, I’d be much more accustomed to dragging notes to barlines or using “extend to” commands - if memory serves me correctly it’s this sort of experience that led Alain Silvestri to make the initial Dorico feature request. (It’s also possibly why the existing “extend to” commands don’t do anything with the caret; they’re expected to be used outside of input mode, after you’ve put a bunch of attacks on the page)
I really don’t think your feature request is outrageous; just that you’re ahead of some of the rest of us 