but it seems that you just say the same as was already said in this article and add nothing new…

That is correct though i did write it independently.

Testers should not waste they time programming complex scripts, it is up to programmer to automate the task.

We differ then. These days a tester must know a programming language to be reasonably competent. Do you really think that all a tester needs to do is record a flow and change number of users from 1 to 100 , run a test and he's done(in which case why have a tester at all)? Besides the comment was that for beginners the proxy recorder harms more than helps because they then feel they don't need to understand the application. You can see this in the JMeter mailing lists sometimes, when the recorded script doesn't work , they have no clue as to what they should do next.

You also say there that "Testers seem to get the impression that all they need to do is record and replay the script and they are done." I would say that your testers got perfectly correct impression Testers should not waste they time programming complex scripts, it is up to programmer to automate the task.

The patch I was discussing there was created specially for that, so the one could record the script and then just replay it. There is no need to update it after recording.

http://theworkaholic.blogspot.com/2010/08/jmeter-with-spring-webflow.html

To reproduce the problem do the following.
1. Add Thread Group and Controller as you did in your example, but not add any HTTP requests yet. Add Regular Expression Extractor as in your example if you wish so.
2. Add HTTP Proxy Server to JMeter workspace. Use your controller as Target Controller.
3. Configure your browser to use JMeter HTTP Proxy Server as proxy.
4. Browse your web application with your web browser.
5. Some HTTP requests will be automatically created under your controller.
6. Check these HTTP requests. You will see that they will include real flow execution keys as parameters instead of ${flowExecutionKey} text. The main task of my little patch is to replace these real keys with "${flowExecutionKey}" text.

Basically the workflow I have given above is typical for any performance testing engineer using JMeter. Nobody is interested in wasting time writing HTTP requests manually for the complex application, so everything is being recorded by HTTP Proxy Server. However, this recording becomes a nightmare if you need to amend these keys manually. Another way is to replace them all using your favorite editor and regexp directly in JMeter data files, but this also is not very interesting thing to do.

Have you tried adding the expression extractor to a controller? It should automatically be used for all HTTP request samplers nested within it. See the image above for where exactly it's inserted.