The thing is... it can be both bad and good.
However, the player should have a choice.
Example 1:
FTL has this. However, it is designed in a way that it sometimes throws incredibly unfair or even random battles at you that ruin your whole progress. At least on easy difficulty, people should be able to reload. Instead, I crashed the game a few times on my relaxing playthroughs because there were some absolutely BS/unfair encounters.
I understand games having something like this in hard difficulty. But in something as random as FTL, people should have a choice, at least in lower difficulty settings.
That, or just decrease the randomness and make encounters more consistent.
Example 2:
The old Bioshock and its hacking system. The game isn't very punishing if you don't succeed. You just lose some health and hacked healing stations are cheap enough, especially when conserving ammo instead of going all-out every battle. However, there is a randomness factor of trap fields often forming rows that are impossible to get around once the water has started flowing.
Vita Chambers revive you pretty quickly and without huge punishment. So consequences are also very low there.
It is still annoying to fail and reloading often is simply faster and easier. And the randomness simply shouldn't be.
Example 3:
Pretty much every game with a thieving/pickpocket mechanic. Failing there can often completely ruin the game, especially because some of them have bugs. Doesn't really matter if it is Fallout, Elder Scrolls, Gothic or whatever... those thieving mechanics have an uncontrollable randomness-factor and consequences are often too severe, making players reload too often.
Punishing the player for failing at a minigame or something that is actually doable isn't a problem. If people forget about it after a while, it is not much of a problem either.
But when pickpocketing is simply casting a hidden die in the background and even high skill levels have a chance to fail, and even worse, making the whole town attack and never forgive you, then save-scumming is simply needed.
That said, save-scumming simply isn't fun either.
Another thing about multiple save slots is when you have to choose between paths in a game. You have a newbie/apprentice time, walking around doing errands, getting to know a little about the factions... and then you have to decide for one of them.
The game should make a save at those points so people can replay the game without having to replay the whole apprentice time.
