Just wait a few weeks, the DLC is going to fix the problem. If it doesn't I can bet they won't continue to sell copies of the game. The only people who are OK with the definitive ending are the small percentage of hardcoe, lifetime Fallout fans. (AKA, these forum members)
Funny, lots of other games have been hugely successful without playing after the end. Like Halo. And Mass Effect 1. And Call of Duty.
Frankly, for most gamers, freeplay after the end isn't necessary. Broken Steel only came about because *everyone* panned the game for having a terrible ending. Gaming publications, gamers, everyone. Here the response is pretty much the other way around; most people are much more pleased at the ending here, except for a few hardcoe TES and FO3 fans who demand freeplay after the end despite the whole "YOU ARE APPROACHING THE ENDGAME, IF YOU HAVE ANYTHING LEFT TO DO, GO DO IT NOW!" message box of doom.
Anyway, AFAIK Obsidian has said they won't do a Broken Steel style DLC. I have to hope they hold true to that and don't cave to the people who want to render the ending worthless.
that's total bull-schitt, they need to add a disclaimer somewhere to that, i wouldn't of wasted the past 7 days playing this game if i'd known that i can't continue after the ending... really pissed off now

They
did add a disclaimer. When you go to do the final quest, a message box pops up and says "You're approaching the climactic final battle. If you have anything you want to do in the wasteland, do so
now, because you'll be locked into your course."
If you just mindlessly clicked that message box without reading it, I have no sympathy for you. In much the same way I don't have sympathy for people who ignore clearly posted warnings and stick their arms in giant industrial meat grinders.
No, that's not possible. They didn't program all the changes that could happen for each different way you can end things. That'd be a heck of alot of work for not much effect.
I dunno, Kiralyn, was there ever
any game that has had that level of postgame content? Oblivion certainly didn't, unless you count removing the Oblivion gates. Fo3 didn't, even with BS, though it made an attempt at it. ME2 didn't, Morrowind didn't... The biggest game with "after the game" content I can think of is Fallout 2, and there it was basically one huge joke, what with the Fallout 2 hint book item, using a random Vault City terminal for 30,000 xp "quest", and hearing random junkies or VC citizens congratulate you on blowing up the Enclave.