I make TONS of save games for several reasons. I mod a lot of Fallout-3 and mods are notorious for causing crashes, when entering new areas, or interacting with things, etc so having a "clean" save that you can back up to is necessary. I also save when I am in a safe area, before I am about to venture into a dangerous area. If I have fought through a dangerous area and I am in a temporarily safe spot, I may make a save there, so I don't have to trudge through the same fights I just finished. And of course, Quicksave is used a LOT (but only the one slot there).
In Fallout-4, aside from the issue of mods, I can see even MORE reason to use save-games.
Constructing settlements, for example. I can easily imagine that you start constructing and spend all kind of resources and create this and that and move that there and this over here... and then decide you don't like it and want to configure things differently. Assuming there's no loss in destroying things you created to try again later (there may be scavenging loss), it would be a LOT easier to just load up the savegame from before you started construction.
With the dialog system the way it is, I can guarantee I'll save before every conversation I have. I don't want to select "Sure" from a dialog menu and then have my character narrate a long story that totally is NOT what I meant to say. The fact we don't know what our character will say until we hear it means I'll be reloading before conversations a LOT. Sometimes just to see what the other options ARE. I may still end up using the dialog choice I would have chosen first... but I may find out that what I thought was a boring answer actually leads to a conversation thread I want to pursue, which the other seemingly-better dialog option does not lead to.