I don't speak on behalf of the PMBR:
The question of whether Fox and Falco are well-designed or not is a very comparative exercise. If you look at Brawl, the reason we say he's poorly designed is because comparatively to the rest of the cast, he is marginally better than even the second best character in the game, the difference in power between MK and other characters seems almost insurmountable. In Melee, I would venture to say that even a bottom tier has a chance at winning against the top tiers, albeit it will be a very, very uphill struggle. And by a chance, I merely mean it is possible but unlikely. By that standard, their balance design is better. Now if you look at Project M, there are more characters clearly designed to be good against spacies like Wario, and most characters are being given anti-spacies counter-measures, further indirectly improving their design from a balance standpoint. In recent tournaments, spacies have been present but not dominating tourneys, which says a lot about the improvements we have made on several members of the cast.
Design is always something you got to view in context.Even without any sizeable changes from Melee, one can say spacies are better designed in the Project M metagame from a balance perspective just because of where the rest of the cast stands. It,s not as clear cut as going "Said character did not change, so he's just as good as he used to be". If you make everyone better, naturally, you are indirectly nerfing the the character. At the same time, you must consider the new characters. Squirtle, Ivysaur, Lucario, Ike, Olimar, Wario, Zero Suit, Diddy, etc... were not part of the melee cast and they bring a new stream of matchups. Then you got added things like Footstool jump (that many forget exist), DACUS, new stage lists, etc... Project M sports a lot of variety that was previously not present in Melee, which changes the metagame drastically.
I actually never had much of a problem with the spacies. If anything, I think characters like Roy in Melee were horribly designed in terms of balance. They used Marth, changed the sweetspots hitboxes haphazardly and called it a day. Mind you, he's incredibly fun to play, but he's weak, and that's because they didn't pour the effort to balance him correctly. Then you got characters like Jiggs that are just built around being as annoying as possible. They are poorly-balanced and defy all rules of smash. Mind you, if you like Jiggs, all the power to you, my friend. I don't like floaties, and we can just agree to disagree.
My point is that yes, they were very good in Melee. Others did not compare. Yet, if you look at Project M, the spacies were improved dramatically simply due to balance changes made to the game.
Edit: Also, if I do not respond, it is because I haven't got the time to be around the forums, being flooded by work and such.