Attack and Sp Attack are not great stats. A special attacker doesn’t use physical attacks, so why do they need any points in Attack? Mixed attackers are generally less efficient at doing their job without speed or bulk to protect them. Do you think there could be more added to these stats to make them more useful so that a Pokemon like Absol and Cacturne don’t have massive dead weight stats that they aren’t using.
Hrrrmm. Well, I do see your point. Mixed attackers have kinda been on a downward slide for the last couple of generations thanks to the gradually increasing options for getting overwhelming power in a single attack stat (particularly now that we have mega evolution). Flexibility is great, but that’s what your teammates are for. And because Game Freak seem to use a Pokémon’s base stat total as a rough guide for how powerful they want it to be, a Pokémon like, for instance, Arbok is wasting a limited number of notional ‘points’ by having 65 base special attack instead of 15; Arbok isn’t going to use special attacks anyway. The trouble is that this is, in theory, a way of helping Pokémon who, like Absol, have moderate scores in attack stats that they will never use… but what could you possibly add to special attack that wouldn’t be just as helpful to Alakazam? My instinct here is that, whatever you try, odds are good you’ll wind up with exactly the same situation as we have now – strongly preferring one stat is still better, just for slightly different reasons. You probably wind up nerfing all defensive Pokémon, but I don’t think this is your intent. The best I can come up with to address this would be such a radical change I’m not even sure I’d want to do it – namely, replace the strict division of physical and special with a spectrum, so that you can have 100% special attacks like Psychic at one end, 100% physical attacks like Close Combat at the other, and a bunch of mixed ones like Thunderpunch being 40% special or Flare Blitz being 20% special. Like I said though, that changes the game so radically as to make it unrecognisable.
I think it’s also worth noting that, if you’re not in a competitive online setting – that is, if you’re just playing through your game, and not paying all that much attention to EV training – then the flexibility of mixed physical/special sets is a significantly bigger deal. Sometimes the difference between a Pokémon who flat out cannot do something and a Pokémon who is merely not very good at it can be much greater than it is on the competitive scene.