So, as a human-only PB, I have a few thoughts.
The first is that even if you're going tri- or bi-form, the human component has a bit of an identity crisis, but I don't think that's a problem-- if it was expanded upon. The reason that we have the "jack of all trades, master of none" problem, I think, is because we can't quite specialize the way the VEATs can, but I think that's an easier fix than it seems. Squids can already do the blasty-blast pretty well, and crabs can tank effectively, from my understanding, albeit the above-mentioned auto-hit for their taunt and/or an aura would be ideal. Toggle suppression might go a long way for both, methinks. But that brings us back to human.
I think the coolest thing about PBs is that, especially with IOs, you can seriously customize a build to specialize, if you so desire. My build is damage heavy because I want my character to be a bit of a blapper, for example, but one could just as easily make a solid blasfender as well. I think in order to add a little more flare to these archetypes, we should lean into that concept a little harder so that, depending on which powers you pick, you're either a blapper or a blasfender.
So I would start by raising the damage modifiers for human form for melee and ranged to 1.0 and .95, respectively. Possibly raise their max damage, as I've seen on an excellent post by @mrfreedom, maybe to 425-450%, but the modifiers for sure, as that will put them below scrappers and stalkers in melee, and on par with dominators in ranged, but below blasters and squids. Next, we have to take a look at the powers.
The first change I'd make to powers is to lower the activation time and/or change the animation of Incandescent Strike. Melee PBs need a smoother rotation, so that we can follow the jab animation of Radiant Strike with maybe a one-two punch (like one of the Energy Melee animations, I can't remember). Incandescent Strike looks cool as a big hit, but the game plays at a bit too fast a pace for it as it is. I might also change the knockback to knockdown on at least some of the moves, primarily Incandescent Strike, Luminous Detonation, and Solar Flare, as turning those to knockdowns (especially the latter two) would give us a little bit of soft CC without costing slots. I don't mind playing with a bit of knockback for flavor, as thematically it makes sense (especially for something like Dawn Strike and even Rad Strike), but as it is, it's excessive.
Next, I would look for opportunities to expand upon PBs healing capabilities. The best (and coolest) idea I've seen so far is to lessen the damage on Photon Seekers and add an AoE heal to them on detonation. I think we might benefit from a third healing option, but that's not my forte. But pick up some Leadership powers and forgo some of the melee options and bickety-bam, you're a blasfender.
Now if we REALLY wanted to lean into the concept of specializing, especially late in the build (as it already is and as it should be), we could co-opt some other abilities to develop an Ancillary Power Pool for PBs and Shades, but that might be getting greedy.
Anyway, that's my two cents. Love this game, love this community, and love my PB. See yall in the City of Heroes!
Edit: Oh, and Mez protection for human especially. We need that real bad.