Having been a long term supporter of RoR (and still am to a degree, it is very good for some things), I recently tried out Tornado. Very, very impressed, I personally have been much more immediately productive with tornado than I was with RoR. Worth a look, YMMV.
It's a personal preference thing. Do you need to? No. Should you? Personal preference.
A lot of people dislike PHP but it does get the job done. However, the only way for you to tell is to try each and see which you like best. As long as PHP serves your needs and you're happy with it, you're fine for the most part.
There are some arguments on technical debt, clean syntax, and scalability. In which case you can explore the other two options. Worth a try.
Disclaimer: I went from PHP to Python. I prefer Python.