That's only for games really seriously infested with DRM. There perhaps, it takes some effort to weed out that stuff. But it's really the most recalcitrant cases. Usually it doesn't take any substantial effort.
> Let alone future support if you plan on issuing patches down the road.
That's unlikely. They might issue updates such as add-ons / expansions and other missing stuff. But they wouldn't issue bug fixes and etc. For instance EA are now releasing their games like Dragon Age: Origins on GOG. They offered their expansions there after the release as a "patch", but they wouldn't make any bug fixes and etc. Such games are way past their production cycle. Clearly EA don't mind extra sales coming from such games. Though quite a lot are still missing.
> That's not even factoring the risk that you are now releasing a super easy to pirate version.
So you are saying they shouldn't sell those games because what, pirates already pirated and still pirate them? That's ridiculous. It's simply saying - we can have more sales, but we shouldn't. That release has no effect on piracy whatsoever. If anything it can actually reduce it, because some might pirate cracked versions because they are DRM-free.