Well Enterprise can't jump 30,000 light years in a reasonable period on time. Discovery can. Captain Pike is already acknowledge, in show, to be one of Starfleet's most decorated starship captains. He likely has whatever pull he wants right now. Add to this the Constitution-class appears to be the class of ship to be on if you want to be somebody in Starfleet, than Captain Christopher Pike has the choice assignment right now as captain of the USS Enterprise. A decade or so later, when Kirk's in command, it might not be as much of a prestige ship, but still enough to earn significant mention with other ranking Starfleet officers and former Starfleet personal. Take it another two decades and it just an older ship. Still useful in the fleet, but not the front line starship class anymore. One more decade after that, then they are seemingly being retired after 50 or more years of service as a class.