I think there is one major obstacle that prevents Superman from being portrayed as smarter. There are essentially 2 things that evolve overtime - the protagonist and the mythos/world around the protagonist. In order for things to fit together well, both have to evolve consistently.
Let's take Batman for example. Batman evolved to be the world's greatest detective over the years. His mythos have also evolved but with that knowledge in mind. The world around Batman is specifically designed to have him solve cases and use his wits over and over again to get out of certain situations. His villains are also built around that idea and are meant to challenge him in that regard.
But with Superman, it's almost as if the Superman mythos evolved overtime without the idea of Superman being very intelligent being there. It's as if the world around Superman was built without taking into account his level of intelligence in the first place. The best example is the Superman/Lex Luthor dynamic and Superman/Batman dynamic. Essentially, one of the themes that has been present in those dynamics for years was the idea that the human mind is capable of keeping up with godlike power. That established theme didn't seem to take into account certain things such as, for example, Superman doing science just as advanced as Lex's (or more) in the Fortress of Solitude. Heck, a large part of the Batman/Superman dynamic is that Batman is the mind while Superman is the muscle. It's been that way since at least the 1980's. But when this dynamic was established, it wasn't with the intention of making Superman look inferior to Batman or to start a pissing war between the fans. The message was that these men were equal and completed each other. Whatever one could do, the other couldn't. And it just so happens that what Batman can do is seen as cooler than what Superman could do in today's age.
It really seems as if there isn't much room for Superman to show off his intelligence in Superman stories. It's not that writers don't know how. It's more that there aren't a lot of ways his intelligence can shine without breaking whatever fans consider to be the status quo of the Superman side of the DC universe. If you stay true to Superman's meant intelligence, people will complain that certain aspects of the Superman mythos have had major changes. If you keep the status quo intact, people will complain that Superman doesn't display his intelligence as often as he should.
That is essentially a problem even MOS had to juggle. It tried to modernize Superman and get rid of all the complaints people had over the years (he's too powerful, too nice, etc.) while still trying to keep as much of the things people identify as part of Superman there. And based on the polarizing reactions, it almost seems as if there is no way to do Superman without causing a major division in fans, both the casual and hardcore ones.