So was Oblivion's. Personally, I don't care; I wish they'd get rid of this "Main Quest" nonsense altogether.
If that is the only thing you do, then yes. It is short. But the game is open on purpose...they WANT you to go and do other things along with the main quest. Explore, do side-quests, do guild quests, track down dragons, find loot, buy a house, craft, fight baddies, etc.
I would suggest you go back and look at the suggestions here. And slow down and enjoy the game!
Oh, absolutely it's about open-ended freedom. Nobody needs to tell me this. I've played the entire series and always had a blast. However, Bethesda really seemed to build up a lot of hype for the main quest and I'm finding it, for the first time in an Elder Scrolls game, interesting and fun. I don't want it to end too quickly, but I've only heard of how short and underwhelming it is in contradiction with what Bethesda always insinuated.