Note that this is because those are gigantic worlds that’s still glowing brightly from the heat they obtained from their very recent formation (these directly imaged planets are usually a few tens of million years old). We should be able to image not-visibly-glowing planets soon, but not as of today.

The Solar System is too old for anything but the Sun to glow (except collisions which are extremely rare too), and brightness of Solar System objects scale to distance to the power of four (2 from dimming sunlight, 2 from the distance itself), so any cold planet rapidly fades into invisibility.