I'm not sure I'd call Stanley Kubrick's movies accessible. Sure, there are less accessible movies out there, but also much more accessible ones. And accessibility is not a bad thing; movies are meant to be watched.

I personally find Kubrick's movies excellent. Rarely perfect, but often highly innovative in one area or another, and all completely different. They range from glacial 2001 to funny Dr Strangelove, to historical costume drama to brutal war movie, and he manages to capture the essence every time.

There are many other deserving directors out there, but it'd be nuts to not consider Kubrick among the greatest directors.