So I was thinking about how I liked the whole process of building your house, and how it reminded me a little of how you had to jump through a bunch of hoops in Morrowind to get your fortress from one of the great houses. Then I got to thinking about all the stuff you can add on in Hearthfire, and it reminded me of how the fortresses in Morrowind were really like small towns, with residents and everything. Then I remembered that you also got some way of defending your estate (Telvanni got animiculi, Redoran got militia and Hlaalu got a bodyguard/mercenary). Then I remembered the DLC in Oblivion, how Battlehorn was guarded by knights, how the Thieves Den had pirates, and how even Frostcrag had imps and a means to make a permanent Atronach which could be used as a follower or, in my case, used as a guard for the main hall. My point is that in all these cases, you had some manner of guards for your awesome new house, but aside from the odd cliff racer they never really had anything to defend against. Here we are now in Hearthfire, and one of the things they added in this DLC is random attacks on your manor, but nobody to defend it other than yourself and maybe your steward.
TLDR: Previous games gave you guards for your house, but enemies never actually attacked your house. In Hearthfire enemies will now attack your house, but you don't have any guards to help defend.
I really hate to nitpick about his, but it seems like such a face-palm moment to me. Now, if I'm wrong and there is a way to get guards in Hearthfire that I missed, I will acknowledge that I stuck my foot in my mouth and slink away.