The issue is really root access for tinkerers and folks who want to tweak NAS' Linux innards and add capabilities not in the base product. QNAP and Synology provide root access via SSH on all their NASes (so does WD on its new MyBook Worlds). Providing direct console connection is just a convenience.
I wouldn't say console / root access is a trend. But I do see it on higher-end NASes, especially those aimed at business users.
And yes, QNAP, Synology, Thecus and NETGEAR are out to take market share from server and high-end storage products!