No, it's not the purpose at all.
I bought an SSD not because I need specifically an SSD, but because I needed another hard disk, and not for the extra GBs.
I currently have 2 operating systems installed on my HDD, both of which are Mac OS X Lion.
I would like to install Windows 7 for video games but I can't have another partition of a different scheme on that HDD, so I'll move both current OSs to the SSD and install Windows on the current HDD.
The cheapest HDD I found is 300 shekels (160GB) and the M4 64GB is 380 shekels, so I figured it's time to upgrade.