Hi Chris,
Few things...
There is one movement holder that Omega sells specifically to make servicing of the module easier. As you have shown it can be done without that holder, but if I were doing a lot of them (I don't and won't if anyone is thinking of asking!) then it would certainly be a handy thing to have to make life easier.
As far as just servicing the base movement, and putting the module on to test it, that may be what people do, but it's not really what Omega calls for. In fact the tech guide for the 3220 says this as the very first thing (after listing tools lubricants, and parts that have been redesigned that should be changed):
"The chronograph is always disassembled in the START position.
The chronograph module must be completely disassembled. All parts should be cleaned carefully."
Emphasis is mine.
There are certainly checks for functionality that must be done on the module after service, and there is an allowed amplitude drop between the chronograph turned on and when turned off, but these are not used to determine if the module is serviced or replaced. It always gets serviced, at least if the job is being done properly.
Your point about the module always running is an important one for those who may think that just because the chronograph isn't running, the module isn't getting any wear - that is a completely false idea.
As I've said many times before in these threads, the modular chronograph isn't more expensive to service than an integrated chronograph is if you send it to Omega - they charge the same for all chronographs. So the "it's more expensive" claim is somewhat midleading. But what is certain is that if you are getting a full and proper service, your options will be much more limited than they are with an integrated chronograph, such as the 7750 based calibers.
If people love these and want them, then buy all means get one. Just understand what it is you are buying before you do so, and what it may mean in terms of servicing down the road (or right away as the case may be).
Cheers, Al