CMake, SCons, etc, all have their pros and cons. They are hardly paragons of virtue though. [Yes, even as a mere "consumer" of CMake (someone who occasionally needs to build packages that use it), I've been bitten and frustrated by it.]
As far as I've found, there really isn't any build tool that really gets everything right -- which suggests that the problem is harder than you suggest. [Although judging from the number of people who try to write their own build tool (most of which languish and eventually die, but cause some pain along the way), it's clear enough that many people think it's a simple problem...]
> autoconf needs to die, die, DIE
Decaf?
It doesn't matter for a "works fine" person how many faults their current tool has or how much smoother "your" tool solves all those problems, they won't listen. Logic doesn't work maybe because it is very hard for them to get used to something new. Maybe because if you haven't experienced any alternatives it is very hard to imagine that something could be better.
It is not just that M4 is a horribly ugly, badly, inconsistent language. You also have about a million leaky caches in the build process to deal with. Autoconf rewrites the build scripts in three stages, each which is cached and also keeps an autom4te.cache directory around. So what happens is that you update something in the M4 build script and then have to spend hours hunting down why the change didn't change anything because some stupid autoconf cache wasn't flushed.
What autoconf has done is to separate free software developers into two categories. Those who can hack the source (the .c and .h files) and those who understand the "autoconf magic." It should be telling that people refer to it as "magic" - it's a fing build system, not rocket science.
The only reason this ugly piece of software has lived on is because people treat it as some kind of magical device and inertia. Configuring and building software is an easy problem. It gets even easier if you finally decide to drop support for 30 year old unices that no one uses. The autoconf team consistently refuses to do that which why the software wont ever become better.
CMake, SCons, Waf and probably half a dozen more tools all do a much better job configuring software than autoconf ever will. People really need to try those alternatives and I'm sure they will realize autoconf needs to die, die, DIE.