Why are inners planets in our Solar System rocky, but in many other solar systems the inner planet gas giants?

Actually Jupiter in the birth of our solar system is almost a bit closer in being a star - it got the right temperature, right mass, and right size. It didn't made it through because the Sun governs it's orbit, and Jupiter's gravity is not yet enough to support its own planets. Gas planets have rocky cores, in which for some reason got the incapability of having solid matter in their planet, which is gravity. When the solar system was born, everything was full of gases and other materials, and a big cloud of stuff and sort of matter was there, then the Sun took power, became a star, and those stuff encircled the Sun until they made shape, yes, you're right, the heavier elements went to the inner planets because those heavier elements were pulled near the Sun, leaving the gaseous stuff outside the solid stuff. So, the other solar systems got gas planets because when their solar system was born, the main cloud that was the base of their solar system's birth is made up of mainly gas. A little amount of heavy stuff, and more and more gas. The heavy stuff built the gas planets' core, and the gas made it's way as the planets' composition.

in those other planetary systems the inner planets that happen to be gas giants are formed that way by a matter of chance in which they were formed based on their composition. The energy generated by the main star(s) of that planetary system may also play a part

The current hypothesis by planetary geologists is that gas giants that are close to their suns moved there AFTER they formed because of gravitational interactions with other massive bodies which changed their orbits. Some of those gas giants are losing their atmospheres because the solar wind from their star is stripping the atmosphere off. Gas giants DO have liquid or solid surfaces and liquid outer cores of nickel and iron, probably with a significant percentage of sulfur as well. (Sulfur lowers the melting point of a nickel-iron alloy.) because they ALL have strong magnetospheres and high magnetic dipole moments. Relatively rapid rotation is also required for a magnetosphere to form. Even though Venus has a molten outer core, it rotates so slowly that its magnetic field is barely detectable at this time. Mar's has remnant magnetic fields, but it's outer core has probably largely crystallized over time. Mars doesn't have enough mass to insulate the liquid core from cooling off and crystallizing over billions of years even though Mars does have relatively rapid rotation.

put your hand over a hot burner 6 inches above and keep it there for 10 minutes....then increase the distance to 12 inches, you'll notice it's not so hot. Now imagine the hot burner is the sun and your hand at various distances are the planets. The closer you are to a burning body for long periods of time, the more cracking and burning occurs. The farther away you are, the less burning there is.

Because GOD made it that way.