the non-cynical explanation is that the lightbulb socket is the form factor that is most easily used by the consumer. Some sort of setup involving changing the lightswitch or the bulb socket might be better, but would also require a bunch of work and risk (live wires!) to install.
We've been using about 50 Hue bulbs for years, without a single one going bust. But I'm sure you're able to buy cheap crap that is... well, crap.
They're not great to have as a renter, though; many of the AC/DC converters were designed for Halogen light-bulbs, and have a minimum wattage requirement, so the more power-efficient LED light-bulbs don't work. Plus, since the fittings are less common than E27, the choice of light-bulbs is much lower.
If solar power and home electric storage batteries become more common, we might start having DC run directly into houses, to avoid the DC/AC conversion from the battery, then AC/DC back to computers/light-bulbs/TVs. But that seems years away!
P.S. smart light-bulbs need to have individual micro-controllers if you want to have colour control. I rarely use the funky colours like green/blue, but I do love being able to go from white light in the morning, to a warmer/orangish light at night.
I'm picturing my future home though, festooned with "cigarette lighter" outlets throughout the house.
But you won't replace all the 15A/30A lines on your home with 12V lines. it's not viable.
But I have a van that I converted to an RV and it has a 12V fridge, 12V fans, 12V pump (for the water), 12V chargers for my phones and of course 12V lighting.
I think a good deal of electronics in a home could be run on 12V DC.
2) Replacing one bulb every few years is much less time/money than a wiring project IMO.
But the cost and difficulty of installation must drastically reduce their appeal. Sure they're not hard to install, but it's probably best not to encourage DIY electrical work.
https://www.screwfix.com/p/tcp-1-gang-1-way-smart-light-swit...
Haven't been zapped either (I'm extremely careful about that, not so much when I was young).
To be sure though I have stopped at the point where a new circuit/breaker would need to be added to the panel, new wiring run. Although I do understand in theory how it is done, how to select the right gauge wire for the circuit, staying within the current limits of the panel....
Obviously, a sane way to do things would be to have a single microcontroller/WiFi module mounted near/inside any of traditional manual light switches, have a single AC/DC convertor near your circuit breaker box, and have it power the whole lighting wiring (from which the microcontroller would draw too) with 9V DC, and now the LEDs inside the lightbulbs will have enough space to cool properly even with size-reduced fittings.
But where is money in doing things the sensible way, right?