I don't think you're wrong that it might be useful for emergencies. But I think you're also right about it not being perfect. It's a compromise between what's desired (functionality of a full-size keyboard) and what's possible to fit into the given form-factor. I actually quite like the way many laptops have an extra key column on the right, where they fit all the caret control keys. It kind of makes me wonder how much smaller all other keys would have to become to fit that extra column. By the way, adding that column could also conveniently solve the problem of Arrow Up/Down keys being so small, because Arrow Up could then "steal" some space from the Shift key, allowing Arrow Down to be full-size as well. Well, that's how my aged Dell notebook has it.
Re punishing myself: I don't code in brainfuck, so it's not like I need to have my AltGr key pressed all the time. Again, it's habitual, but I have zero issues with pressing AltGr to input numbers or characters like @ or $. I see no usability difference between pressing Right Shift + any key in the top row on a US keyboard, and pressing Right Alt + Right Shift + any key in the top row on a LT keyboard. What do you do with your right thumb when you're entering these characters? Probably nothing. I just put it to use.
Re numpad: some laptops offer numpad emulation via Fn, which alleviates the issue a bit. Sadly, not all do, and some of those who do, suck at it. But if implemented properly, it's actually quite convenient. Maybe V could have that as well, although having these keypad characters even in small print would probably make the keyboard appear more cluttered, which might not be welcome by the design department.