We'll call it part of my interest in how programmers work. The truth is, as a text-editor junkie, my impulse is to say "meh, IDEs are passe," but I think that's probably unfair, and in my writing IDE post I think I recognized--by analogy--their worth. In any-case there's something sort of nifty about PIDA: rather than recreate tools, it just makes use of what's already there: the editor is emacs (or vim), the version control system is whatever you want (and already use). PIDA just brings all these things together in a nifty little package.
On the one hand, it's not a really big deal. Cobbling together working software from a bunch of different existing tools isn't particularly new. This is sort of the basis of unix-like computing, and further more it tracks the ways most people/geeks actually use computers: by finding the best tools for all of the jobs they have to do and then using them. This way of interacting seems to hold true for command-line and graphical users, I think. So rather than recreate the wheel, PIDA just uses all the existing wheels. The saddest part is that we don't see more things like this in the graphical application world.
The end result of this mode of application development is that we're given/build powerful tools that function in familiar ways and that are more powerful as a result of their integrations.
And that's about it.
I initially thought that this was going to be a really long and really blathering post about integrated tools, and the power of open source/free software to allow tools to be combined rather than be forced to compete. While these are indeed important issues, they're pretty self explanatory, and IDEs like PIDA provide a great example of how this can be the case, so much so that I find myself saying "why aren't there more programs like this?"
Why not indeed?