Believe me, companions have improved. The very, very old episodes of Doctor who, companions did nothing but scream and twist their ankle. Now at least they are useful, even if they do still screw things up.
And to give them some credit, there are times when the Doctor would be truly fucked without them.
I didn't realise Simon Pegg was in Dr. Who (This was just after his success with Shaun because I'd never seen Spaced) until just after I'd seen Shaun even then I had to go back and watch the episode again to make sure. Oh cool thing for those interested in the episode "The Doctor's Wife", the writer for it Neil Gaiman wrote the brilliant film Stardust as well as some great Sandman comics.