I never thought SL/ASL represented leaders well. By all accounts, the real counterpart leader was always on the front, in the battle. It was the job of sergeants and lieutenants to be leading battles. Sure, in certain situations, they would hang back with the big weapon or from a vantage point, directing fire but for the most part they were on the front.
In game terms, this almost never happens. Rather, low-level leaders are in the rear area, rallying units instead of being on the from line. Stacking with a low level leader is rarely good. It offers little combat incentive and usually exposes the units to additional penalties such as leader-loss/leader-break task checks. The single benefit of preventing cowering, in my opinion, is not sufficient to merit this tactic.
I would like to see this rule modified slightly to add some incentive to have leaders with the troops. For instance, the Japanese leader rule stating they increase the moral of all the units stack with them is an excellent starting point. It does not have to be any more intensive than this. I might stack leaders now. Have them prevent PTCs from IFT results - excellent idea. It has almost no impact on the rules and the logic is consistent.
Yet, the problem with this kind of tinkering is it causes new issues. For instance, I like the Command Control idea in SASL. Units do not perform as you would like them unless they can actually see the leader. Yet, this puts the leader in the middle of the troops rather than the front line.
Also, I would like to see new types of leaders. The old 7-0 to 10-3 is limiting especially for campaign games. HASL and CGs have this problem the most. For instance, in KGP, the Germans are an exclusively elite force, SS to be exact, so that the lowest moral is an eight, since all the units are 6-5-8s. Yet, the leaders start at 7-0, worst than the infantry. If officers came from the ranks, why would they have an inferior moral? Even if these were possible, the German side tends to accumulate several of these during the campaign, hardly reasonable even for this late in the war. What is needed is the lowest leaders be 8-0, 9-0, 9-1 and so on.