Publishers dont put games on steam for the weak drm protection it provides, they do it for market visibility. Games on steam sell well. Publishers want their software to sell well. Its a no brainer.
However, if you have a huge release like GTA that effortlessly sells millions at a time whenever its released, even a small percentage of pirated copies adds up very easily and thyll of course want to look into minimising that as best they can.
Like I noted before, if we use a conservative figure like only 1,000,000 people on PC get the game and only 1% (10,000) where a minority portion of pirates who just cant wait for a crack if the drm holds up, thats around £500,000 they wouldnt have been able to earn if they used the easily cracked steam drm.
If we assume that more than one million on pc end up wanting the game, which I think we can, then the reward for this risk continues to be more lucrative.