They're safer because they have a higher success rate.
Why reboot? Just recast, redesign and move forward.
I was reminded the other day that there have been several movie versions of events surrounding the gunfight at the O.K. corral - I've never felt it necessary to "ignore" one in order to enjoy another.
Agreed, it worked for Gene in 87 to just set the show ahead to the 24th century and go from there. A show set in the 25th century with a ship exploring strange new worlds etc. would work.