How is that? Pruned nodes "benefit the network" just like any other full node, with just one exception: they are not helpful with the stupid bootstrap process in the current (experimental) implementation of the protocol, nothing else, not a tiny bit of any sign of being inferior compared to a historian full node ... I just made it up 
And that is why I think we have fundamentally different ideas of how Bitcoin should function, based on your past response about how verification of block data is not necessary, etc. If your view is that block data is not important, then I believe that you'll probably disagree with everything that I say. We can only argue that more Archival Full Nodes are going to benefit the network only if there is a shortage of them that makes syncing hard for new nodes that come online or puts extra pressure on the existing Archival Full Nodes.
I don't think this is the case since we have enough of them to supply the historical blockchain.
I believe that there is nothing wrong with making it more available. Having more "archival" full nodes would be far more useful for initial synchronization both in terms of it's speed and availability. I'm aware that pruned nodes can almost function like an "archival" full node but I fail to see how it would be as beneficial than the other, given that the bulk of the benefits falls on the user using the full node. If the blockchain size grows even further, people that are hosting them on RPis and servers may not want to run it anymore.I don't think this is the case since we have enough of them to supply the historical blockchain.