The problem with moving Wallace around is twofold, imo:
1. He doesn't run a variety of routes well. Wallace is tremendously fast in a straight line, but like a lot of fast guys he's long legged and has a long stride, which hurts his quickness. This is part of the reason why he's not a threat on precise routes or timing routes generally (he's also lazy, imo, at least in his route running). That makes him predictable for the defense. Are you worried about Wallace running a jerk route, or out and ups, in and outs, in cuts or out cuts? Not particularly. When he runs those routes he looks average, usually below average. With Wallace you have to worry about the post, the flag, the go and the drag... and to a lesser extent the speed out. That's where he's at his best.
There's a reason you tend to see quicker receivers who have long speed deficiencies playing inside the hashes. It's a quick, precise game in there, or a game for physically dominating guys (like tight ends). That is the exact opposite of who Wallace is and what he does well. If you put him inside a lot defensive coordinators are just going to pat you on the back for making their jobs easier.