We've had a DW re-boot news to me, I thought we had a continuation of the show (after it was uncancelled). Just with a budget more fit for the 21st century.
Oh for God's sake. Reboot, revival, remake, reimagining, whatever. The term reboot is used so widely as to mean any new take on an existing property. Of course it's a continuation of the old show, but it's done in a different style to that of the 1970s and 1960s (shorter episodes, standalone stories as oppose to multiple-parters, different tone etc). The point is to show that old shows can be revived for a modern audience.
There are several issues to brining back shows (not that I am disagreeing with your point that then can be brought back)
1.>Executives want the instant ratings hit
2.>Audiances can be rather fickle, and aren't generally willing to give shows a chance to become success.
3.>Due to Executies cancelling shows, a part of the audiance is unwilling to invest time in a show that will likely be cancelled. Thus leading to that shows cancellation.
4.>Some Executives appear to believe that shows should be written for the lowest common denominator.
5.>Executives don't always look at the long term profit margin for a show. Sure a show could lose money initally or not make a huge amount. Reality TV show can be great for the instant profit, but do you really think that "America's got talent 2010" will still be being shown in reruns (and thus generating money) in 2050?