Of course, (as several people prefer to continuously point out for some reason) you could ferment with plastic buckets, or carboys, or old kegs as well. One of the 'benefits' of a conical fermenter is in dropping the trub and easy racking while maintaining the yeast cake. If you aren't planning on doing one of those two things I personally don't see the appeal of a conical. I don't think the 'magic' of 60 degree walls will make your beer better.
At least for me, I want to try a conical to see if I find the whole fermentation process more pleasant. I went with a plastic version to give it a test go for a reasonable cost. The dump valve and racking cane are important for me as they are key parts of the conical experience. I'd like to try making a small beer, dropping the trub, racking the beer off and pouring a big beer on the yeast bed thing. I might also try collecting yeast for future batches. I think a conical might facilitate those experiments. Besides, I like playing with new beer toys.
If I love it, I'll either upgrade to a SS version or keep my plastic if its working. Otherwise, I'll stick to my carboys.