Giants, IMO, were another great idea for Skyrim, that ended up getting short shrift in the development department. If you remember the 1st E-3 trailer, they were initially portrayed as a solemn, almost tragic race trudging along with their mammoth herds. You could walk along with them, and unless you assaulted them, they didn't seem to mind the company. We cut to the actual game, and their is virtually no in game back story to them. You can't talk with them, rather, get too close and it's "to the moon, Alice". There are no questlines to speak of, except the generic randoms, to "Go kill a giant" , which my character would say, "Why?". There aren't any reasons other than JarlSkalds' " they are a problem" Female Giants, or giant offspring are no-where to be seen, either, though this carries out for most of the beastiary in Skyrim. Another instance where the game comes up shallow, unfortunately.
Don't forget too that you were also supposed to be able to speak with giants. As a matter of fact, it doesn't make sense in the final game when it comes down to specific certain quests, kind of like how it ultimately doesn't make sense how in Windhelm Rolff still uses the term "Pit bait" and some people refer to the prison in Windhelm as the "Bloodworks" (as a matter of fact, there's even a piece of hallway behind a wall in the Windhelm Barracks which I presume to be left over from when the Pit was still in the accessible game world). Truthfully, the final layout of the Windhelm Barracks really doesn't make much sense at all, especially since they seem to have arena-type holding cells and no arena, and how it's kind of weird and twisty, if you know what I mean (like turning, going up, entering guard quarters, going through a somewhat lengthy corridor, around a corner, weird dead end, another turn just to go back down again into the dungeon, why would it be set up like this).