Netflix UK also got access to the past series, so I am not sure if that was part of the deal with Discovery. Makes you wonder if the old series are worth more to them, than the new?
I think, yes, getting all the old shows was obviously something they would've stipulated, but I think ultimately the money they paid was largely for exclusive rights to Discovery. They've had Trek shows in some of their regions in the past, and they know its global appeal, so whilst a nice boost from having the old shows is attractive for them, Netflix are smart enough to know they'll make big bucks from being the only place in the world that you can legally watch the new show - Trek's fans will pay for it. Hell, that's one reason CBS themselves have put it behind a pay wall.