Even though this post is 1 month old, i'd still like to comment this because it contains wrong information.
Well they may not be a security downgrade for individuals in practice, but they lower the overall security of the network...
The overall
security does NOT get lowered by running a pruned node.
The 'security' depends on the amount of miner/hashrate. Not on the amount of nodes.
an user that wants to run a pruned node ultimately depends on other people running full nodes in order to download the network,
This applies to anyone who wants to run a node. Doesn't matter whether pruned or not.
EACH node needs to download the blockchain from other peers when setting up.
so ideally, we want more full nodes, not just more pruned modes, otherwise like I say, you are damaging the overall network.
They are NOT damaging the network. They do NOT contribute to the overall health of the network, but definitely do NOT damage the network.
By the way, non-pruned nodes which do not allow incoming connections do also NOT contribute to the overall health of the network since they do not distribute old blocks to new peers.