Airlines Purposely Overbooking Flights?

Maybe this belongs in the rant but I'm curious how you guys feel about airlines that overbook their flights on purpose. Do you think it's a fair way to do business or should it not be allowed to happen?

Situation: I had a connecting flight in Chicago yesterday and was travelling with my 14 month old (I'm also pregnant but within the flight limit) and they had overbooked the flight and we got pushed to the next flight which was the NEXT DAY. I was so so upset. I paid for this ticket at least a month in advance so I feel like I should be given a seat that I paid for. My layover was less than an hour so I didn't bother bringing a stroller and really I wasn't prepared to do more than 5-6 hours of travelling. I was coming from my mom's and going back home and I have stuff for me and my son there because we travel there a lot so I didn't have a suitcase of supplies and clothes just a diaper bag with me.

Just curious how you all feel about airlines being able to do this?