While Batman is an exceptionally intelligent guy, and also the perfect physical specimen of a guy, he's still just a guy. A flesh-and blood, albeit very rich, guy with no superpowers.
And so are (most of) his Rogues' Gallery. He's a street-level hero fighting street-level criminals. So a Batman TV show wouldn't need the same kind of effects-heavy budget that super-powered shows like Supergirl or the Flash do.
That's not to say that a Batman TV show should have the production value of DIY YouTube channel. But with a focus on sleuthing, crime-solving and realistic hand-to-hand fight scenes, the show could allocate its budget towards amazing sets (more on that later) and practical bat gadgetry (also more on that later) instead of having to make it rain thousands of dollars every episode on a 30-second CGI fight scene. Until the Clayface episode, that's gonna be an expensive one.