I have been pondering this thought recently: why are there seven SI base units?
Is there any relationship between this and any more fundamental physical fact or phenomenon?
Is there a absolute minimal set of base units?
For example, it seems that the candela is an example of a base unit that is not strictly necessary – it just relates power to a weighted approximation to how bright a light source is perceived to be. It is an extremely useful unit (and I am by no means advocating that it be removed as a base unit), but not strictly necessary as a base unit.
Best Answer
I think the "Base quantities" have nothing to do with their fundamentalities. If you ask me I prefer that Space(Length), Time, Mass and Charge to be the most fundamental ones. As you said there is no need to take such things as Light intensity or Current intensity as fundamental quantities. What I get from SI is they tried to take those quantities as basic which are easily measurable so we wouldn't have difficulties in the measurements. That's it.