To argue for the 2% healing advantage, I'll say this. It can be a game changer in a lot of close situations. If you are barely in kill percentages, healing is nice. As Rosa, you really can't let him heal all the way for 3 minutes. This is unlike most MUs, where she can just sit there and gravity pull you for 6 minutes if she is up by 1%. I think that is all Pac Mains are really getting at, it forces approaches. That alone is powerful, but if you lose the first stock to ragealina at 40% it doesn't matter.
---
Roy is actually pretty scary. His nair is insanity, and should never get you shieldgrabbed or OOS'd ever, unless you try and land the last hit and get powershielded. Don't use his fair and bair to space! You use nair as your aerial combatant, beating out their moves with either its speed, range, or safety, depending on the MU. When they start trying to dodge or do something tricky, then you hit fair. A fresh fair or bair will kill surprisingly early. Same with ftilt. Dtilt is super strong in footsies and again, great on shield. Utilt can kill later, and combos early. Dthrow is really nice, and if they start getting complacent you can walk forward ftilt or fsmash them for their airdodge mashings.
Roy has a cool niche against tether grabbers, since his nair/dtilt/jab is crazy pressure against them, and defensive options are super scary with his f-smash floating around. But against someone like Marth/Ike? Oh Lawdy, not so fun. But, he is nice against a good chunk of characters. This may seem obvious, but unless they can keep him from mixing it up (with a large sword, gimping him, oppressive something something...) he usually holds the better risk/reward, again because of fsmash. And that is his 50% kill move, once you are in real kill range his pivot ftilt, fair, bair, nair, jab -> blazer, armor'd blazer, and more do the job well.
Being fast in the air, even with bad acceleration, is nice... especially when your strategy is to come in with nair and crush whatever they try and do, and if they shield just start jabbing the **** outta them.
I think high reward characters in general have a good presence in tournament brackets, because your wins come that much easier. It is less stressful, and your opponent can't adapt as well if the game is already over. Of course, on the flip side, he can die before you learn your opponent. So why not learn your opponent with someone, then pull out Roy if they have bad OOS or if you are landing smashes but not getting your kills!
Oh, and uair is a solid juggler. Sweetspotted it hurts, and a sourspot puts you just hovering above roy which is bad bad bad. With its landing lag, I would guess that sour uair -> sweet uair is a kill confirm. Its also really safe on shield.
So, when you look at his landing lag, don't look at all the aerials. You aren't gonna fair or bair unless you are getting a hit and want a kill. You'll be landing with nair in neutral, and uair if you can hit it will give you higher reward than lots of stuff.
His combos are vertical things, like dthrow utilt utilt uair, dthrow uair -> kill dodge with fair/bair.... and the infamous tap you with something -> full side B combo that is deadly, easy, and powerful.
Edgeguarding is surprisingly versatile, you have your aerials, counter, reverse blazer stagespike, and charging Flare Blade at the ledge mixups.
tldr; I think the fact that Ryo pulls out Roy in some MUs should tell you something. Especially since it is commonly accepted that Ike doesn't lose any MU horribly, and Diddy/Ryu/ZSS are some of the MUs that he likes Roy.
But, alas... when someone hears all this and still asks, who is he better than? I dunno. But he is a valuable pocket, much like many around his general power level. Its not so much a lack of strengths as an annoyingly present weakness; but in MUs where the weakness isn't so bad, the powers really come to play.
Srsly, nair-> jab and nair-dtilt makes tether grabbers not want to shield at all. But, any other dodge is super risky so you either shield or just try and battle a disjoint, which can be hard when he is really really fast.