What happened to metamorphic viruses?

Do virus writers still attempt to make metamorphic or polymorphic code or have antiviruses over come this?

Out of curiosity, why are all metamorphic and polymorphic viruses file-infectors? Wouldn’t it be a lot simpler to make a standalone program (worm) that rewrites itself? Furthermore for a file-infector to work it needs to know whether it has infected a file before, which would be difficult.

Do virus writers still attempt to make metamorphic or polymorphic code
Well yeah, Polymorphic would be easier to write. Reason: if the goal is for going undetected (like hiding from a traditional av scanner: basically blacklist detecting) why make it more complex then needed. I won't get into the specifics as this isn't a malware programming forum >:-D
have antiviruses over come this?
Depending on the AV, but to keep it as simple as possible. Yes to some degree.
file-infector to work it needs to know whether it has infected a file before
It all depends on how its coded. example just infecting executable files or a specific ones like .bat files in a certian and/or all folders :o
Wouldn't it be a lot simpler to make a standalone program (worm) that rewrites itself?
Of course

What is?

Most certainly not this forum.