[miniupuchaty]

I don't have this problem in practise. It's not "break flow to switch modes" for me. I don't type this way. There's always as much movement as there's typing, especially while programming. Even when writing prose I exit the insert mode each time I think of what to write next making this always a good "undo point".

If I make a typo while in the insert mode I just remove last character or last word. I guess you could argue that this is something that undo should also cover but I don't see much need for that.

I'm not in the insert mode, exiting to normal mode for movement and undo. I'm in the normal mode entering insert mode to write.

[eviks]

While the inferiority of your workflow doesn't matter to you, it's still a point against undo being "solved" by vim

[fwip]

What problem does a magical "does what I mean" undo solve that pressing ^W or ^H doesn't? At a minimum, your "superior workflow" is "<Esc>ui" or "^Ou", both of which are more keystrokes and require your editor to read your mind.