Re:PhDs will build a new skill set. (Score 1)

this is totally true. not only that, but assuming you are at a halfway decent school, you will work with lots of smart people and learn many different things. you will have an opoportunity to be exposed to many different projects and viewpoints. finally, if you are worried about how `practical' it is, don't do a theory topic: work in systems or networking or another field where you write software. trust me, it's not hard to find projects where you will write tons of code and learn more than you ever wanted to about random computer topics of choice. on the other hand, typically no-one will tell you what to do and you have to be willing to be independent and come up with your own ideas and motivation.