Its the regulation of expression but the sequences themselves are never expressed.
If the raison d'etre of some piece of DNA is the regulation of neighboring pieces, then if it does so, that would constitute its expression, right? (We are nit-picking after all... Just ignore this.)
[W]hy are [CNEs] conserved?
Because they're good at causing themselves to be copied? Most "functional" genes use the complete organism as a means to get themselves copied and spread around. Maybe the CNEs are just hitching a ride? (Selfish gene talk, Dawkins and all that.)