I'm a sympathiser with the op's view that protective devices should ideally be rated 'as low as possible' for the load in question. .
I shall try to convince you again.
OK, but I really doubt that there is anything to say that we haven't all said already, in previous discussions.
[quoteThat's the whole point - the cpd is not there to be 'ideal for the load'.
It does nothing for the load. It is to stop the cable melting.
We have all agreed that it should be able to stop the supply cable melting - which, indeed, is what is required by the regs. However, that does not, to my mind, alter the fact that it makes sense to make use of the ability of the device to give some degree of protection to other things in the circuit if/when that is possible.
A 3A mcb would not 'save' any of the OP's lamps. If he had only one 60W lamp in his house there would be absolutely no benefit from fitting a ¼A mcb.
I agree that it cannot save lamps, but that doesn't necessarily mean that it cannot protect anything.
In any event, we've been through all this before and agreed that the conventional 6A protection of a lighting circuit is probably there to protect accessories and pendant cables, even though, particularly if wired in 1.5mm² cable, a much higher rating could be used to protect the supply cable alone.
We've also previously discussed the situation in which internal wires and components in appliances could 'burst into flames' under fault conditions, with currents far lower than those which would damage the supply cable. If the situation is such (e.g. dedicated circuit) that it would be possible to have protection far lower than actually required for the supply cable, that fire risk would be reduced.
What about the fuses in plugs? Even if the flex was capable of standing much higher currents, I would still consider it appropriate to use 3A or 1A fuses where appropriate to the load - again, to afford some protection (and, potentially, reduced fire risk) to whatever is on the end of the cable.
Kind Regards, John.