Not so much.

The reason UNICOM is text only under squawkbox is that under network regs you still have to type on UNICOM.  Not everyone on VATSIM can receive voice, so text is required so they can "benefit" from UNICOM as well.  FSInn allows you to use voice on UNICOM, however, you also have to type your intentions on UNICOM as well so that text only pilots are able to see it.  There are some users who are deaf, so they would be unable to hear you announce that you're landing on runway 17R and they taxi into position for departure on the same runway because you used voice over text, for example.