The Stealth Skills Rebalanced mod for Skyrim does all of this, and pretty well, I think. It makes harder locks prohibitively difficult, so that you have to invest at least a few perks if you want to crack them without tearing your hair out. Not sure what they could do to scale up the difficulty of terminals, other than putting more words on the screen, but reducing the amount of attempts we can make to begin with seems like the easiest solution. Try hacking a Very Hard terminal in only two attempts.
As for save scumming, I don't think Bethesda should bother trying to restrict that in any way. But I do think they should try to create failstates where we have a reason not to save scum. For hacking, there was no point in having the terminal get locked down after running out of attempts, since we could just save scum or even better, back out of the terminal on our last attempt. And Bethesda actually encouraged backing out in their hacking tutorial - so in the end I'd rather they just drop the lockout completely, and have the terminal's passwords reset automatically after we run out of attempts. Maybe set off an alarm or a trap if we fail, in places where it's appropriate.
The real gameplay mechanic that encourages (I daresay necessitates) save scumming, though, is pickpocketing. If you get caught pickpocketing, there's really not much to do but reload your save. There are a few things that Bethesda can do, but I'd prefer they just completely overhaul the pickpocketing system to begin with. It hasn't really changed at all since Daggerfall (!).