See, that's the thing. People who
don't have all the tools to hand think that the connections are over-rated. People who
do have more of the tools to hand think that it's much more important than is realized by people who
don't have all the tools to hand.
It's the blub[0] paradox all over again. I would suggest that you haven't (yet) learned enough to realize that the connections are much deeper, stronger, and important than you realize.
It may well be that you don't need to know that the derivative of 3x^2 is 6x, but the influence on working with discrete math of a deeper understanding of continuous math is real, but subtle and hard to explain. Like Spock said when McCoy asked what it was like to be dead:
McCoy: Come on Spock this is me, McCoy!! You really
have been where no one has been before, can't
you tell me what it felt like?
Spock: It would be impossible to discuss the subject
without a common frame of reference.
McCoy: You're joking - you mean I have to die before
we can discuss your insight on death?
We can't all learn everything. I'm not advocating that everyone should get a PhD in cross-disciplinary math subjects, just as I'm not advocating that everyone should become fluent in Japanese, Russian, and Finnish, or that everyone should become fluent in Scheme, Haskell, and Erlang. What I am saying is that I, who do have a PhD in math, believe that the connections are more extensive and useful than you realize.
[0] http://www.paulgraham.com/avg.html