As everyone says, the pictures are better because you have to use your own imagination to provide said pictures given the medium can’t!
You can be anything and go anywhere in any time in your radio script. Having a drama set in Alpha Centuri is a real possibility (and I’d be surprised only if it hasn’t been done already).
Listening makes you appreciate the words more in how they flow and increases sense of appropriate word being used for the right occasion. Anything that isn’t appropriate will jar and “break” your enjoyment of the drama.
There are openings for writers though I wish the BBC would expand the short story slot rather than reduce it. It can’t cost them that much to put on a short story and it varies programming. You can have too much news!
Anyone can write in with scripts, which is welcome.
I’ve heard some wonderful plays and dramas, set in all kinds of worlds. And Doctor Who is a regular on Radio 4 Extra both as audio books and scripts especially written for radio. Both types are great.