Yep, the architects of the Constitution were pretty smart. They were smart enough to know that they couldn't predict the future, which is why they designed a system of government that could be adapted to meet the needs of every generation. In an age when the average life expectancy was 50,  modern medicine meant leeches, and most people never moved away from where they were born, healthcare wasn't a national issue. Today, it is. 

There are built-in boundaries in the Constitution in the form of checks and balances and separation of powers. How those are lived out in every age is the ongoing work of democracy. I'm not in agreement with the notion that government can fix every societal problem, but I do believe in robust debate about how government can best serve us in the here and now.

I don't look on that as a lack of boundaries but, rather, as getting the best use out of the magnificent  constitutional apparatus the Founders left us.