If you look at virtually every single German news source today.....slam after slam on Grenell's comments, the hyped suggestion to kick him out of Germany, and the negativity over Trump. So you reach a point (as the non-German) of asking....what is driving this German anti-Trump theatrics?
1. First, the SPD Party is literally dying, and probably has been so since the Schroeder era (1998-2005). A fair number of Germans will say that the CDU moved so far to the center and to the left....that there virtually nothing that the SPD stands for anymore. Added to this problem, a fair number of working class Germans don't think the SPD really speaks for them anymore.....as it did in the 1950s, 1960s and 1970s.
To make up for that trend, the SPD folks need some 'clobbering' going on, and just about any non-German target would work, but especially Trump since he is so anti-socialistic in nature.
2. The German public has taken to laughing over politics and the various gimmicks. You can turn on the TV and view comedians attacking various parties and politicians.....nightly. There is no respect much left, so the the politicians are inventing ways to get attention now.
3. Merkling. German kids around three years ago...invented a new word. When you have a leader who should lead, but mostly just stands there and observes.....doing almost nothing in terms of reaction, then you are merkling. The kids started to use it to describe Merkel, their local mayors, the various politicians that appear on TV, their local ministers and priests, etc. Twelve-year old kids will laugh over the way that politicians now appear on TV and perform merkling.
4. The public media folks (ARD, and ZDF) are having a problem with viewership. From the 15-to-25 year old group....I doubt if more than 10-percent watch their version of the news on an average basis. Readership of newspapers is declining. The number of Germans who watch public forum shows on the German public TV? I would suggest that fewer than five-percent watch it on a regular basis.
5. The discussion over the 'Teddy-Bear' era? From 2013 to spring of 2016.....Germans were in the midst of the 'Teddy-Bear' era where anything said about migrants and refugees....was happy and positive. Today? The 'Teddy-Bear' era is long gone, and well over half the population are asking questions. They don't buy into the political answers of 2016 anymore.
All of this leads onto the problem of political stability, and frankly.....some Germans are fed up with the Merkel period.....but they can't really find anything to replace it. They would laugh if you suggested the SPD or Green Party folks. The AfD gets an even bigger laugh. You can sense frustration with the general working-class public and the desire to 'fire' most of the folks in the political arena.
So they are worried. The Trump enthusiasm came out of this Tea Party era, and here in Germany are the same basic ingredients. When Grenell suggests that he might talk on conservative ideals, or he might present more radical suggestions (lessening taxes, downsizing the government, opening up business markets, improving the job market, etc). All of this business would destroy they've spent decades building. The mere suggestion that you'd decrease the national sales tax from 19-percent to 13-percent? Oh my.
So they really need to get out in front and suppress the public appeal of Trumpism, and hope to kick Ambassador Grenell out. In the process....the German ambassador will likely be given walking papers, and a number of missteps will occur with Chancellor Merkel unable to really explain this in public. And the appeal of the SPD and liberal left parties? Of all the daily problems that Germans have....Trump isn't on the top ten list, or probably even the top fifty list....except for the tariff business. And if you had a real EU....they would have wrapped up the TTIP deal and you probably wouldn't be in the middle of this mess today.
Sit back and enjoy the entertainment. The French are greatly amused.