Well that's what I'm saying. It's MU related. Falcon's neutral game which is basically dashdance grab and nair works really well against Lucas' and M2's kits (maybe Pit's too), and their combo weights are absolutely great for Falcon to get off. Lucas has it really bad, with regards to Falcon combos.
You see, Falcon doesn't care that Lucas has a godlike recovery. Because Lucas is a semi FF and a lightweight, upthrow -> knee can become a kill option as early as 70%. Being a lightweight causes Lucas to suffer really bad knockback, and also give Falcon ample time to read DI for throw follow ups. Being a semi FF sends him at a perfect trajectory for knee follow ups from uthrow and sometimes dthrow, and lessens the effectiveness of survival DI against the knee. A random Falcon kick (which Falcon can definitely land in neutral) becomes extremely scary for Lucas once he's at 100%. Falcon can actually edgeguard tethers fairly well by letting go of the ledge into DJ bair, similarish to Marth.
A pocket Falcon is really nice to have if your main happens to struggle a lot against Lucas, M2, and maybe Pit. But like you said, Falcon is an honest character. It takes lots of work and strong fundamentals to truly be good with him. So for now, only guys like JamieHR can whip out a pocket Falcon and win against a solid Lucas main like Neon. But at a mid level, where most people are, it's such a great counter pick.
As for Fox, yeah sometimes I prefer playing lighter characters like Roy vs him because getting knocked down (and being able to tech) is a much better alternative than getting waveshined into upsmash/dsmash/waveshine/grab. If you watch Sethlon's set with Mango at Whobo, Mango is barely able to make meaningful conversions off shine.