Ooh goodie, if there's a problem building texinfo on my machine I can read the docs in HTML. Of course, I'm fucked if I want to write my own documentation for my own code.
Yes, texinfo itself might only be 1.5MB, but you seem to have forgotten to take into account its dependencies. Those which are required by texinfo and not by perl come to something like 50MB. Which is one reason that I generally don't bother with texinfo. 50MB is a *lot* of storage to dedicate to a documentation system.
And finally, "It's standard GNU fare (./configure; make; make install), so that means it'll likely build on most Unixy platforms (including Mac OS X). Dunno about MS Windows" indicates not only a great deal of ignorance (GNU fare can be exceedingly hard to build on a great many UNIXy and non-UNIXy platforms (VMS, anyone?) due to incompatible extensions in GNU make and in the GNU shell which Linux-using idiots try to call /bin/sh when they shouldn't, and so on) but also a distressing lack of concern for a significant proportion of the user base.