Its been over 10 years since the game launched. Big source engine modifications and the game although pushed to its source limits have a lot of potential for mods. But a lot of it is locked behind closely guarded source code modifications.
With SDK a lot of door would open, you could change the way game works something you cannot do now.
One of these things a lot of people still on demand is proper VR mod. While Crowbar Collective FAQ say it would need to redo a lot of levels and meshes we can clearly see looking at HL2 VR that its not the case at all.
While yes, guns, UI and motion sickness tools would be implemented it has already ben done by Flat to VR team. And as of today its stands as Overwhelmingly Positive on steam reviews.
Yes this is despite the props are way to big for actual VR perspective but I don't see anyone complaining.
I do not see why Crowbar Collective would not give access to portions of the source code to Flat to VR team to make a mod like HL2 VR. I'm pretty sure there were people that would love to work on it, they have dedicated branch for BMS VR but of course its riddled with bugs because it runs on old BMS build using HL2 EP2 VR mod.
And so I urge Crowbar collecctive to consider this. Coming from modders to modders there's nothing worse when you have something you love, you could improve or change but you can't because your hands are tight and people who have will to do it don't see a sense in it.
Among other things that SDK would enable for modders to do.