In north India people make similar rangoli designs on festive occasions. As the name implies (rang = colour), coloured powders are used. I don't think these are done every day -- maybe someone who knows better can educate me on this.
I doubt if the people who put the kolam meditate on the meaning of what they're doing. It's part of keeping an auspicious house, like putting jasmine in one's hair and doing the daily puja. To me it has to do with demarcating, and perhaps protecting, the threshhold, the line between the outside world and home.