The market and lamp designers have done this already with LED desk lamps and many formerly standard fittings.
This is not progress, and is both environmentally and financially abusive.
So a light with integrated LEDs can have a lifetime that's much longer than one with replaceable bulbs.
Additionally, the total complexity is a lot lower for lights with integrated LEDs. It's just not true that lights without replaceable bulbs are less environmentally friendly -- in many cases it's the opposite.
preferrably soldered on a big metal part
An obvious solution to which would be soldering the LED to a metal connector that mates with a heatsink. We could call it an "LED bulb".
Of the assorted LED bulbs, fittings and sealed LED only products I've so far owned few have got to even 20% of claimed life before colour temperature or brightness has become pitiful. The only exceptions thus far are in my monitors (not exactly room level illumination), and in a few year old torch - but that has usage in hundreds rather than tens of thousands of hours.
So it looks like we really need some replaceable LEDs. Manufacturers would, of course, prefer to sell another desk lamp or kitchen fitting when the LED inevitably deteriorates.
You'd think so, but houses still have bayonet fittings so LED bulbs are standardizing on those (or on screw fittings, I guess, in parts of the world that use those.)
GU10 fittings do seem popular with the smaller bulbs, though. LEDs can get away with using these for higher output bulbs because they're so much more efficient.
However the trend shows that flexibility of directly building in long living LEDs is increasing.
Out of curiosity I was just searching for desk lamps on Amazon and first two pages were all LED-bases, which makes sense, since those are all design elements (sometimes of better, sometimes worse designs) where LED gives lot's of freedom.
Looking for ceiling lights gives a few classic connectors, but also lots of LED.
(This might be accelerated since I'm in EU, which banned classic lightbulbs for energy reasons ... over alternatives which are a waste issue)
> The bayonet mount is alive in most of the English-speaking world (except for North America). It has been mostly phased out in France but it can still be found.
And right now we're at a time where LEDs are rolled out everywhere, giving much more free hands to lamp designers.