No half in their right mind would feed it 100% straight. The universal standard has been set (that scrummies can feed the ball to their side) and so long as it isn't obscenely bad they will continue to get away with it.
To say it has eliminated tighthead scrums is not necessarily true. Tightheads are most often won when (by winning the hit and putting the opposing scrum in a bad position and/or a well timed shove) the team feeding the ball is blown off of it or forced into an error due to the dominance of the other scrum. It usually isn't because of a hooker winning a "hooking contest". Although they occasionally pull off a great hook to win the ball, the opportunity is given to them by a whole pack. That less tightheads are being won reflects a few things. They are more common at schoolboy level due to the large variations in size and scrumming skill between teams, but at a professional level the packs tend to be very well drilled at scrummaging. Even someone who is "rubbish" like Maafu can usually prevent a total demolition of their scrum (except for against England) and the skill of the front rowers is reflected in the speed of their engagement. A team is rarely knocked off the ball outright just from the hit alone, though they may be destabilised by a better scrum. The players tend to be good enough to recover from this position or at least minimise the degree to which their position is compromised, meaning that they may not lose the feed, but may suffer from poor ball (either from going backwards or from being forced to send the ball out the wrong scrum channel. Also, the skill of the hookers is shown by their ability to win scrums where they are on the back foot (noting that they do of course have the advantage of knowing when the ball is coming in, unlike their opponent).
So, after that extended (and probably confusing) rant on scrummaging, the fact that rugby is now very professional and scrummaging is increasingly well coached is probably explains the lack of tightheads as much as crooked feeds. Not to say they aren't occurring, but due to the skill of the packs, rarely does one dominate another to the extent that they win a scrum outright. More often, they force poor ball and therefore an error or turnover later.
In answer to the thread's actual question - no, all halfbacks feed the ball to their side. So long as it is in the channel refs tend to be very lenient.
EDIT: having read the article posted above, it seems that my experience of the modern game reflects the changing nature of scrummaging. While stability remains important, it is more of a contest revolving around shifting the other team off the ball than a direct contest for the strike. I cannot say whether one is better than the other, as I have only played in the more recent style.
As for the question of culpability in scrum penalties, and the number of resets caused by pushing before the ball is in, I agree with the article, but would say that often deciding who is at fault for a scrum collapse is not as hard as it is made to look. Still, eliminating the problem largely would be helpful (and not pushing before the ball means less reset scrums, which is good).
Also, does anyone else think that once the ball has reached the number 8's feet, the attacking team should be allowed to collapse the scrum? They do it to minimise ground lost and give the halfback cleaner ball, so it becomes a reset scrum. However, if the rule were to be that the second a scrum collapses, the opposition flankers can unbind and go for the ball, people would stop doing that quicksmart, the dominant team would keep the advantage and we could avoid another typical cause of reset scrums.
All this scrumming business probably needs its own thread.