CBS didn't really inherit Trek until after ENT got canceled. While Trek fans may be clamoring for a new Trek series, Trek is really just one
of many properties that CBS owns. In a way, the success of the last two Trek movies by Paramount may have mitigated the need for a new Trek series to keep the brand afloat.
Additionally, the first-run syndicated drama market and UPN were the major factors for new Trek shows, things that CBS doesn't have to contend with.