I think they need to do both. Keep their staff focused on official fixes and feature improvements, and release a devkit for the modders. Doing those two things will show their community they want to do anything and everything they can to make the game better. It also takes the pressure off of them to make the game all things to all people, as the mod community can fill in any gaps and provide fixes, features, and content that CDPR can't or won't devote resources to.
At this point CDPR needs to attack this problem from every angle they can. I think the 1.1 patch shows us that they just can't move fast enough by themselves to satisfy the community. It's not really their fault, time and resource limitations exist and humans can only troubleshoot and fix so fast. Allowing modders to jump on it essentially adds hundreds of devs to the effort, even if their work is not "officially supported".
It's tricky, really. 'Cause then they'd have to also account for those in a way. Or you'd have situations where a fix would break your game if you have X or Y mod installed. Granted, modders also update their stuff as the game get patched, but overall there'd be more moving parts with the potential to break the game. On the other hand, though, if their patches continue to lay the groundwork - stability and performance - enabling, if not outright supporting, the modding effort could help.
Last issue with modding the game at this stage is, as I see it, the fact that a truckload of systems and mechanics are still stuck in the production pipeline. Fine tuning placeholder mechanics and systems is a wasted effort. And, sadly, most of the systems currently in the game feel like that - placeholders. NCPD hustles, crafting, street cred, perk trees, gear, the stash, the cars, the housing, the shops... They're all minimalist, generic, bland, broken or just... not there. Cars may drive better, we might get our hair's shadow back or, as it seems it's needed now, our shadow back, we might get X or Y perk work as described - but all these are pretty much small improvements for a game that is still in a very early stage of development.