The partition is created if and only if the Windows 7 installer partitions the drive (e.g., if you have it installing into a block of unpartitioned space). If the drive had already been partitioned prior to install and you are installing into an existing partition, the 100MB system partition is not created.
And no, you don't need this partition for general use. You need it if you want to BitLocker-encrypt your main partition (and I think it might also facilitate VHD booting, though I don't remember). For 99% of people, it's not needed, and it's not going to cause any problems down the road if you don't have it (but it doesn't hurt to have it, so that's why the installer creates it by default, if given the opportunity to do so).