The only potential con I can find of raising it is from a redhat solution thing (https://access.redhat.com/solutions/99913)

Raising the limit may increase the memory consumption on the server. There is no immediate consumption of the memory, as this will be used only when the software requests, but it can allow a larger application footprint on the server.

So I guess it just means that apps are less constrained so when an app or game is particularly a ram hog it can eat up more ram