In addition to not being very useful, the Virtual Hosts > VM limit setting can cause problems if vCenter or high capacity VM hosts are used. The column is defined as an unsigned tinyint so the maximum value is 255. The web code won't let you enter anything above 100 by default, configurable in conf.php. Situations where you'd want more than 100 or possibly 255 VMs assigned to a host are becoming more and more common.
Rather than reworking things by altering the column definition, I propose removing it altogether.