After taking a quick look at the code, it appears that the Chisel obsidian does not even come close to being substitutable for vanilla obsidian in the production of a Nether Portal.

I've never looked too deep into Minecraft's internals, but my knowledge of Java suggests that a separate chisel block extending Obsidian should be able to trigger the same mechanisms that produce a regular Nether Portal.

As such, I'm requesting the change in the hopes that we will someday see Nether Portals that need no special housing to look nice.

Nope, not how it works. Vanilla checks specifically for vanilla obsidian. Nothing we can do.