But of course, teams wouldn't shift against a hitter who uses all fields. The shift isn't a pro-active defensive strategy - it's a response, a reaction to hitters who have a demonstrated tendency to NOT use the whole field, but (typically) to pull everything. If a given hitter hits ground balls and line drives to the right side some 90% of the time, it only makes sense to defend against that. If the hitter cannot adjust... well, it's no different than a hitter who cannot adjust to sliders low and away. He's out. If he's out too much, he's out of work, and the club finds a hitter who can adjust.
Moreover - the shift doesn't affect a hitter's control of the strike zone. If a given hitter is able to work the count, and work walks a decent % of the time, no shift is going to prevent that.
Shifts are most effective against hitters who put lots of ball in play on the ground, predominantly on one side of the field. So employing shifts means that hitters with that profile are less valuable - even if they're hitting long home runs occasionally.
The effect of the tighter seams - less tendency of pitches to break - is perhaps more a problem, since it may be unbalancing the game in favor of hitters in general. If that's the case, though, there are several time-honored solutions, in addition to adjusting the ball manufacture to raise the seams a bit: the mound could be raised again; the strike zone could be expanded (or should I say, the defined strike zone per the rule book could be enforced?).
None of this will bring back "small ball," for those that pine for that, though. If what you really want is more ground balls going through infields, more runners on base, etc., then you need to force players to play in sub-optimal defensive positions (ban shifts), or perhaps find a way to speed up the infields.
Thinking about it, I wonder how much of the longing for the "good old days" when more grounders got through the infield is really an artifact of the fact that many of us grew up in the era of plastic infield grass (with concrete underneath), which tended to be faster. I mean, we all know that what most of us see as "right," as the way things "should be," is whatever way those things were when we were in our formative years. That's just normal human behavior.