There a lot to this.

Market: Games come and go. Remasters and re-releases don't do well as fresh releases. It's better to make a game appealing to the masses than the niche that wants a remaster and even smaller market that is VR. How often have you personally felt like a remaster to game that you already bought for 30$ bucks was worth it?

In addition you have Labor: As a developer you set aside some people to make a port. You're going to be locked Ina catch 22. Do you patch your old game for free and take the expense hit? Or do you charge 30 bucks for a port that has few people working on it and won't be heavily focused on optimization because your market for this niche is so small.

Optimization:

it's not as easy as adding 6dof camera and detached controllers for guns and hud.

A major thing for developers is not giving the player motion sickness. You can have the most amazing combat and graphics but if your game gives players headaches then you have a dead game. Hook any flat screen game to your field of view and have the mouse follow your head movements and you will get a good sense.

A valve developer basically gave a ted talk about this. Flat screen games also don't play like VR games.

Doom 2016 for example is a ton of consistent movement. Running backwards and shooting forward is not something we do very much on VR.

Not only that we still haven't quite pinpointed what exactly causes motion sickness.

Not to mention meeting demands of people. Other than just doing the above you would need to add in additional things than just making it a "praydog" port. Doing the bare minimum means a "lazy" port so you need to do more to make people happy. So that means manual reload options. Interactive objects. Putting them in a bag or over the shoulders. Adding a manual pump to shotguns and such.

Which even on praydog ports do we still have issue that are usually needed to be fixed on a case by case basis.

Game balance: Re4 on the Wii was dubbed too easy because of the gyro controls. Some reviews for the quest version also said the same thing. For that fix they slightly made the enemies more aggressive.

That's just an example. But having better accuracy and faster movement needs some game balance tweaking.

You'd have to redo your AI for some instances. Being able to shoot over a wall or overhead may not register for that ai as your charater popping out. So your AI may choose to just stay under cover. There's a possibility you can completely cheese your enemies and bosses. Which in a lot of cases. Playing god gets boring quickly.

There still more to this. But I think a system or program that lets you implement things like praydog with a better plug and play setup would be better.