Reinstating old mechanics for nostalgia's sake would mean bringing back the old Substitute blocking Rapid Spin which is outright wrong. In a way some would say that the spin bug also served to decentralize the metagame as teams were much more readily able to prevent Rapid Spin (Its why VILtar was so fucking good) and Gengar was not as omnipotent as a result of that.
With regards to Baton Pass, I'd say that a good baton pass team can be effective in advance, however not broken. Ingrain/Pass is the only thing i'd consider banning, for the sole purpose that now Sleep Talk has been drastically nerfed to the point of being treated as a novelty set. This means that any defensive oriented team is more prone to Smeargle setting up.
Of course, even that wouldn't be considered as broken but rather a flaw of the defensive team in the first place. In the end, it would end up being a mindgame between the baton pass team trying to prevent the phazer from destroying the chain before ingrain which sounds like a perfectly healthy meta. Even then, Hazers destroy all baton pass chains and Perish Song keeps them on their toes. Not to mention their prone-ness to getting the short end of the stick in terms of critical hit attacks.