It's just plain ridiculous that the ballast (supposedly a part of the fitting) is now considered a disposable item! Unlike the old Thorn G81006.4 units which worked for many years in the factory they came from then a good few more years in moderate to heavy use in my rellies' house. These are now due to be replaced with magnetic ballasts and electronic starters.
BG
Well, I don't think it is so much different to the pure magnetic ballast era.
I do remember a new installation in 90's, when after some 100's of hours about 20% of the VS magnetic ballasts were just faulty (mostly loose contact of the magnet wire in the connector).
The fault presented itself as just flashy lamp (it was thermally dependent), so first the maintenance guy suspected faulty lamps and starters, moreover when messing up with the fixtures when replacing the lamps and starters makes it working for a while again. So it took about a year to figure that out...
And it all were VS ballasts - just a faulty batch. The supplier had replaced them, but nobody had paid the extra time the maintenance guy had to spend on servicing new lighting.
Of course, when those faulty units are already replaced on an older installation, it then does appear failure free. But it does not mean it was so reliable technology already from the point it was bought new.
And another aspect: Over the decades the lamp life had improved quite a lot by manufacturers quite sucessfuly adressing the normal wear mechanisms. But the ballast life remained essentially the same - it is assumed it's life being sufficient. So it then happens more frequently, when the ballast life ends before the lamp.
So I would rather say it became nearly unnecessary to make the lamps replaceable...