Thanks flowman for returning us all to sanity.
I think what Bokkenrijder is referring to is more likely an arrival via G5 (Bern-Zurich). As one of those "guilty" TMA/approach controllers at LSGG I can assure you that whenever possible, co-ordination is effected to avoid unnecessary frequency changes.
The fact is, as flowman said, the airspace is divided vertically and as a result, you have to cross a number of sectors while in descent. If it wasn't so, you'd have to do the same horizontally anyway so no win there. The upper sectors (through which all said freq changes occur) ARE very busy. What would you prefer, fewer frequency changes but an overloaded sector?
Now on to the weather. Like a large number of pilots, I'm sure that you actually have very little knowledge of the amount of co-ordination that goes on on your behalf. If you're arriving LSGG during the day from the direction of Zurich and, for example, start avoiding on first call to the geneva TMA sector(128.9), we first have to call the military as they tend to be a bit twitchy about aircraft disappearing off these days! (military training areas on BOTH sides of the airway). Then we have to call the Zurich upper sector, whose airspace you're still in (IF you're turning left, you're head on to their arrivals in descent). Then we have to call the Geneva upper sector, whose airspace you'll be descending through but not in contact with. Finally, this also has to be arranged with approach who may or may not have their own requirements. All the while, of course, taking terrain clearance into account (how many 16,000 ft mountains to complicate matters around Heathrow/Amsterdam/Paris) as well as our other traffic. Believe me, we don't have much time to sit around with our thumbs in warm, dark places when there's weather about.
While I don't for a second claim that all is peachy here - the vast majority of my colleagues are highly competent and far more accommodating than you think (360 around the Matterhorn anyone?).
Rant mode off. See you at 7. am.
Bon Soirée!