There is no reduction in security.
It becomes much easier to pretend some blocks don't exist to selected targets, and get them to accept selectively rewritten history for just long enough to rip them off.
This security risk is balanced by the correspondingly increased number of nodes, given an equivolent Bitcoin Network Cost, where:
Bitcoin Network Cost = Data Size * Decentralization.
So the net result is no decrease in security.
We can expect a marginal increase in security as the node maintenance cost becomes less 'chunky'.