Mud-slinging is as old as politics itself, definitely, and the endpoint of a disagreement could more readily end in bloodshed before, so I agree with the first part of what you said.
It just seems like the difference between then and now was risk-taking vs. being grounded. I feel like the conservatives of old were really all about being grounded and sticking with what works, whereas the liberal side of things was to take a big risk on something that could have a big benefit. Sometimes it worked, sometimes it bombed.
Also, the people who were elected were certainly never "getting along" on the campaign trail and in front of the cameras, but they at least sat down at the same table and tried to compromise on things when the time came for it. Now, it's all a game of chicken, and they seem to be taking it all personally. Some of the biggest radicals (on both sides) seriously think that the people on the other side of the aisle are actually evil. If they can stall someone out (even if it means destroying a piece of the country's structure: jobs, credit ratings, whatever), they jump on it.
I sorta play both sides... I try to be sensible, but I don't think that I need to become so disillusioned that I can't dream once in a while. And one of my dreams is that the American public will actually grow at some point to match the "immediate gratification" technology that we have now, and then become an informed society. But that isn't happening right now even remotely. Someone on one side can call certain rapes "legitimate", for instance, and get called out by the medical community at large, and STILL poll at least 20-30% support from his constituency. And the media will report it, but not actually call them out on it. That's downright scary.
The introduction of the uber-right-wing elements has changed everything. The Democrats are now the "conservatives" (as the term used to mean), the Republicans have been taken over by scared zealots who use hyperbole like oxygen, and there aren't even really any truly "liberal" risk-takers at all anymore in the mainstream parties.
So, the idea of a third party is definitely enticing, but with things as they are, it's just not practical. At least, it isn't on the presidential-election level; there isn't a speech or person alive today that would get enough people riled up to all vote on a third party. If you really want a legitimate third party to come up in this country, you need to do one of two things: 1) convince a currently elected president/senator/etc. to form a splinter party (probably not going to happen as long as so much money is involved), or 2) start a "grassroots" (*wince*, I HATE that word) campaign that gets a lot of people elected locally, and then slowly build up to the bigger positions.
The Tea Party almost did that second option, but they actually annexed the "Republican" brand for help as they were coming up, and pushed out the people who used to call that label home. Now, folks like Romney (who, you're right, isn't the devil incarnate) have to pander to those people, which makes him look really dangerous to liberals who HATE the fringe-politics that the Tea Party represents. I reject Romney's policies on reasonable grounds, and I wouldn't spew a gang of bullsh*t at him. Obama has done plenty that I dislike, but he's also started the ball rolling on a lot of other things that I wanted to see happen, so chances are, he's locked in my vote this time around. I know this is shallow, but I also like the class he's displayed under fire from all the bullsh*t coming his way.
I do have to wonder, though, if the pandering to the far-right is going to manifest itself in some policy decisions if Romney actually gets in. I don't think he cave in, but if he did, then yes, I'd think him "more dangerous than Bush"... but only then.
I wish there was a third party that really represented me, but Gary Johnson? Jill Stein? I just don't think their platforms are evolved enough, and they certainly don't have the support. Anyway, my two cents...