1. Playing Devils Advocate. The issue with secret warps is that they could be misued. There is nothing stopping anyone for example /tp to someone and then setting a secret warp to that location for use or misuse later (unfortunately misuse has happened in the past).
2. The ability to /tp to somebody makes secret warps redundant, the only way to have someplace secret is therefore to ALSO remove /tp.
Therefore if we do allow secret warps we should also remove /tp. Its the only way to actually really have anything secret.
If we value the ability to /tp and want to keep it, then we should not have secret warps.
If you think I'm paranoid, blame it on 6 years of EvE Online.