i dont know what i want to do with 32bit processing power though :/
32-bit controllers are 3.3V. It allows me to use more powerful modern devices - audio-codecs, FPGA, SRAM, USB, LCD etc.
But it's also requires from me to use more advanced technologies. Modern chips are produced not as DIP chips. So if 8-bit "shields" I've made myself since this is faster-cheaper, then 32-bit board is faster-cheaper to make by ordering or buying ready-to-use.
The answer "why" is simple 32/8=4. Four times more work.
"There are 128-bit chips," this is my 32-bit mantra.