You know, my roommate and eternal smash rival said the exact same thing about Lucario's Aura, that it rewards bad play, to which I responded, "Lucario players who play badly get utterly stomped." which they do, which I do when I make the wrong judgements at the wrong time in a match.
When I first played Lucario when I got the game, and saw what happened to his hitboxes; stunted range (which doesn't scale with the aura), lopped off lingering hitboxes, without much apparent tradeoff; my reaction was essentially "ah crap". At that point I knew the recovery got a boost and scaled with aura, and that felt like just a consolation prize at best. It wasn't until I first saw how much the aura scaling had been overclocked that I realized where Lucario's strengths are.
The way I see it, Lucario's aura scaling grants great rewards for smart play, and really only puts a band-aid on a poor match at best.
Say for instance Lucario's opponent comes out swinging, plays smart, and very quickly stacks up lots of damage on Lucario while taking very little in return: great for Lucario, right? He gets a big aura boost and can quickly turn the match around. Lucario can turn the match around, that doesn't mean he will. If Lucario's opponent is playing well and not falling for things, getting that aura boost is practically moot anyway if Lucario can't get those hits in. Mind you Lucario isn't exactly gifted with great up-close tools compared to much of what we're up against, further compounding that situation. The biggest boon Lucario really gets with Aura scaling, at least as far as punishing it goes, is Force Palm range, Aura Sphere swelling, and a longer recovery to work with. And if the opponent character is a particularly hard hitter, who can easily KO Lucario well before the aura scaling powers up to ludicrous levels, then staging any kind of comeback becomes really really difficult. At that point, Lucario cannot afford to make even one punishable mistake, or the stock is gone. And if Lucario hasn't damaged his opponent much before losing the first stock, then the extra aura boost for being behind becomes little more than a pity prize. I can tell you from experience: really not a great position to be in, especially when other characters can comeback, whose KO moves' power isn't proportional to how hurt they are.
On the other hand, if Lucario plays smart, minimizes the damage he takes while gradually tacking more on to the opponent, it grants a very cozy kind of damage buffer zone. Lucario won't be able to get great KO power until he gets a good aura boost, but that's fine, since the more the opponent takes damage, the less aura boosting Lucario needs to get that KO, and thus the less he needs to stick his neck out for the aura scaling. It puts the ball in Lucario's court and allows him to play the match on his terms, rather than struggling in a risky uphill battle for that comeback. And yes in some cases, if the player wants to, it could mean a tactical decision to allow the opponent to hurt Lucario a little and build up his aura. It may even get the opponent to lower their guard, give them a sense of security (I'm making a comeback! Yay!) in which they might be more inclined to take punishable risks. I personally wouldn't recommend the tactic, not unless, say, Lucario had practically 0% aura buildup, the opponent has lots of damage built up, the timer is going down and you don't want to go to Sudden Death.
Still, the point is, the aura scaling is simply a tool in the Lucario player's arsenal. And like all tools, it yields the best results with intelligent use.
