Hi. All I can say is that the head lamps in the vast majority of vacuum cleaners quickly failed. Not all, and in fact the Panasonic bulbs usually lasted the lifetime, but most failed. The 12v Hoover bulb was a lot better than the 240v bulbs, but they too had a high faliure rate.
To be honest, I don't think UK customers were all that bothered about headlamps and only had them because that was what the cleaner came with. There were only two models of Hoover Junior with headlamps which were a choice if you like, as you could buy one of those or the standard model. All the senior cleaners in the Hoover range had bulbs. As did our Starlight, but later that was taken off when it was renamed Junior Deluxe.
Once the mainstream Junior with headlight was discontinued, they were only sold with headlamps as exclusive lines. Even the Senior U4186 went down this road in the early 1980s. Some of the Goblin Housemaid and Commander cleaners had a choice of headlamp model or not. Electrolux has never had a headlamp on any of it's upright. Now Electrolux uprights had always been stupidly good sellers, so maybe it was finally recognised by the others that a headlamp was just not an important feature.
Not that I'm saying I don't like the headlamps, because I do. I think they look rather swish.