There could be good reasons we wouldn't see von Neumann probes. They could be extremely dangerous to deploy similar to the arguments that are currently being made against autonomous weapons systems. That might result in them having many built in limitations such as needing to phone back periodically or being saddled with multiple redundant systems or safeguards that would prevent them from mutating into something that could harm the originating civilization.
Also don't forget that the purpose of the probes is exploration and/or resource harvesting. For exploration you only need a handful of probes at each star system and they may depart after completing their survey which would result in a very small footprint. For resource extraction you need some means of transporting the resources back to where they will be used in a timely manner which puts limits on the effective distance at which they can operate.
A civilization may even decide that it's pointless to explore the entire galaxy this way since it would take millions of years to gather and transmit the information, what government do you know of that's capable of planning over that kind of timescale?
