The disk space used is not significantly higher and if it's a bother, they can run a pruned node.
if you prune you are then offering less network decentralised security service for the peers. as you no longer become a FULL node source of blockdata for new peers.
This disincentivizes people to run Bitcoin Nodes, and the network will be less decentralized, hurting the higher pillar of the Bitcoin Network.
It doesn't
With a hard drive of 2-4 Tb, you'll have no issue storing blockchain data for a long, long time. And it doesn't cost you up to $50
yep hard drives are cheap so keeping the full data is helping the higher pillar of the bitcoin network, and doesnt hurt the individual because hard drives are cheap.. thus non issue.. however pruning hurts the higher pillar of the bitcoin network