can you explain why these modules can not be distributed?
if the 'old system' can not be used on any machine except those with the same setup as the original, how can modules from that system be distributed any better?
There is really not all that much of a difference as far as portability is concerned.
The problem is that the old style is often not portable to the computer you are writing the code on, since your installation might have changed since pike was installed.
The new style requires you to write your own configure tests (you can use the PIKE_INSTALL_DIR and such to include aclocal.m4 from pike, if you really want to, but there are not all that many relevant tests to reuse in there currently, the C-compiler tests, perhaps, but AC_PROG_CC works just fine usually)