I like the modern world a lot. It lets me be a philosophy professor and use Wikipedia and not die of cholera. I know that the ability of the modern world to make all this stuff work out depends on a whole bunch of institutions -- publicly subsidized education, telecommunications networks, public sanitation, and a financial system behind it all -- working properly. These are complex institutions, and there are plenty of ways that they could fail. While markets have their place in making sure many institutions operate in a socially beneficial way, there are lots of ways markets could fail, and then we need government to regulate. Properly regulating complicated things that could break down in many ways requires long bills. As Steve Benen writes, "That’s to be expected. We live in an advanced 21st-century superpower, and legislation often deals with complex issues."
I think a lot of ordinary Republicans don't share this basic picture of how the modern world operates. You get Sue Lowden talking about the good old days when you paid your doctor with chickens. There's less appreciation of the importance and complexity of modern institutions, and thus of the importance of government in carefully managing them. Since they don't see the problems that big government with long bills is meant to solve, the whole enterprise looks unnecessary -- and suspicious. It could all be giveaways to interest groups (which does happen a lot). Or death panels for grandma (which doesn't).
Democrats generally agree that government has an importance place in making sure other modern institutions don't fail. That of course requires that government doesn't fail, and we recognize myriad ways in which that could happen. Falling under the control of wealth and prejudice are among the ways to which we're the most sensitized. Keeping the modern world from chewing itself up requires constant vigilance from public-spirited people -- and long bills with complicated solutions to complicated problems.