I think there is a cultural issue out there which affects German politics...

The journalist's statement is a bit oversimplyfied. There are many conflicting non-economic issues, like European integration (Turkey!), status and role of immigrants in Germany, energy policy, internal security and civil rights etc. etc...

The main difference is the election system: first-past-the-post versus relative majority system.

First off, the culture wars don't rage nearly as venomously in Germany as they do in the US, but that doesn't mean there's no political/ideological polarization. A hefty portion of the vote is determined by religion and class. If you're catholic you're way more likely to vote CDU, unless you're lower or lower-middle class and preferably a member of a labor union. If you're protestant or have no official religious affiliation (as many people in the east do) and/or are unionized, you're far more likely to vote SPD. This is why the SPD gained a huge structural advantage from the reunification (what with catholics becoming a minority nationwide), even as it has been steadily loosing union support, as the power of organized labor has been on the decline just as it has in the US.

Secondly, it's true though that Germany isn't nearly as polarized as the US. There are currently way more swing voters in Germany than in the US (especially when you take the 2004 elections as a standard). I would guestimate the percentage of swing voters in the current elections anywhere between 20% and 40%.

Final point, ideological diversity is hampered by the parliamentary system - especially the fact that parties mostly vote as blocs. So the views and votes of the individual representative matter far less than they do in the US. Which makes the system less democratic, in the sense that there's less room for individual views; but at the same time, it also makes German politics less personality-driven.

If you can't convince them, confuse them. (Harry S. Truman)

Shouldn't the US have more diverse parties, as they have much more divisive issues they vote on?

1.  There are 3 minor parties in the USA
(a) the Libertarian Party
(b) The Green Party
(c) The Constitution Party
(d) other parties (socialist, communist, etc don't show up on the radar screen)

2.  (a) The US has a "winner-take-all" system. In other words, in a local Congressional or Senate election, if you get the majority vote vote, you get the seat.  So, if the Libertarians got 8%, The Greens got 7%, the Constitution Party got 6%, they don't get a seat in the House of Representatives. You need to win the majority of the votes to get a seat.

(b) In the US  the President, which is elected in a separate election, forms the cabinet.  So, Bill Clinton was the Dem President and formed a Dem. administration (ministers in Europe or secretaries in the US), despite the fact, that the Congress was Rep.

So you had a Dem executive branch - administration, Rep. legislature.

3.  Like many things in life - winner-take-all is good and bad.
(a)  Its good, because it creates a stability.  You don't have to enter into  a coalition with the other parties to form a government.  
(b)) Its bad, because the third parties do not have real voice in the government.  

(c)
However, recently, the 3rd parties in close elections have been playing a crucial role.

Presidential Candidate     Vote Total     Pct     Party
George W. Bush (W)     2,912,790     48.850     Rep
Al Gore     2,912,253             48.841     Dem
Ralph Nader     97,421     1.633                     Green
Patrick J. Buchanan     17,412     0.292             Reform
Harry Browne     16,102     0.270               Libertarian

Some argue, and the Greens disagree, that if the Greens voted for Gore, he would have won.   Greens further argue, that Al Gore "sold-out" the progressive politics and therefore, lost.  (Its another topic)

Similary, recently in the state of Washington, if the Libertarians voted for the Rep. candidate, the Dem governor would have lost.

4.  The state of New York has the following parties:
a. Dem
b. Rep
c. Conservative
d.  Liberal
e. Libertarian
f. (maybe others)