These days CORs are highly dependant on Phantom Roll recast timer in Legion. In that event every minute counts when you enter and it is not uncommon to do multiple COR rotations in an alliance (or even two alliances). In that setting starting and keeping 11 chain is almost impossible since you have pretty much only 1 shot at rolling for each party (busting or having to reroll wastes too much precious time). Imagine three CORs having to wait 60s to reroll each party in alliance - that's 10% of event time wasted by everyone just standing around and waiting for their buffs to be put up. And repeating this process several times..?
Thus, in Legion, Random Deal having a high chance at restoring Phantom Roll is a highly beneficial thing. Same goes for restoring Summoner's Shock Squall timers or Scholar's Alacrity-Stun timers.

Phantom Roll recast with merits and gear can be brought down to 45s (or 15s if you get lucky with 11).

Essentially this change is aimed at putting more pressure on CORs, SCHs and SMNs in Legion. In any other event if you want to avoid Random Dealing your Phantom roll, you just wait half a minute and aim for that Fold/SnakeEye etc. Similarly, your SCHs not having Stun up and ready is not a big deal aside from Legion (and maaaaybeeee Provenance Watcher).

Legion is going to get interesting when Perfect Defence, Embrava and now Random Deal all get nerfed.