Protonerd:
As to cheating: no. I do not see it the same way. I work in the semicon industry and I know from experience: with novadays technology all that can be implemented on silicon on a tiny module which does not eat up any mentionable room on the PCB is worth it (even on this small module the biggest part is the SD-card and the audio amp which you need anyway) ! Hardware is cheap but if you set out to load it on the Arduino, you will soon end up with no memory. So I want my Arduino to be the command center and distribute the task to dedicated modules on the PCB. Some controllers even have dedicated embedded mp3 player, idea is the same. Do it in HW and save on SW.
It's indeed not really cheating, but it just removes the challenge from making the things a bit ^^
Personally, i only feel comfortable using such all in one solution ic's once i've solved the problem myself once the hard way 
(or died trying XD). Maybe it's also because i'm a programmer by trade, and writing a bit more complicated software for the arduino is part of the fun/challenge for me (i'm finally starting to learn some proper C++, i'm a C# developer). If it's just some modules with some simple communication towards them... that just takes away the entire challenge XD.
On my saber, the only library i used (on a maple mini) was one that gave me a very precise delay(down to nearly individual clock cycles), allowing me to easily drive the ws2812 ledstring without needing a library ^^. there are tons of libraries out there for driving such leds, but it's just too much fun to write my own code :p. And a challenge to be driving such timing sensitive ledstrings, and at the same time be playing audio on the same microcontroller :D.
I love a bit of a programming challenge :).