If you stick to the titles, it doesn't make much difference in legibility: http://www.sciencedirect.com/science/article/pii/S0042698907002830. You could argue that it makes the page more easy to scan because titles stand out more.
There are a few other things to consider though. Language is one of the things computers and algorithms aren't very good in. You can set up some easy rules for 90% of the cases, but those other 10% require a whole lot of work.
For example: CSS can capitalize every first letter of every word within the element. Now that's easy, but I want words like 'the', 'a', 'to' etc not capitalized so we need to make our own implementation. With names it becomes even more interesting. In some countries there are words within the family name that need to be lowercase (Vincent van Gogh) and in other countries they do require uppercase (Dara O'Briain). At this point, the developer is starting to look angry at you.
So, yes. In my opinion there are definitely some cons and they outweigh the pros by far. Why not empower the copywriter and let him or her decide when and when not to use uppercase? It doesn't require more resources and gives the copywriter the feeling of control (imagine the reaction of the copy-writer when he purposely wrote something in lowercase and then the system decides for him it needs to be uppercase).