I have to strongly disagree with the notion that Combat skills are weak or have no serious effect. If anything, they are stronger than before. And I feel like have to provide some sort of counterpoint here, since no-one else has done so.
That being said, it is true that Leadership and Technology are better aptitudes. There's a few reasons for this; not only do these help improve the performance of the entire fleet, but they also help to improve the player's ship. Some of the fleet-buffing skills are not just considered bonuses, but outright essential - officers, carrier doctrine and loadout design most prominently. There are three skills in technology that are essential for a build oriented around improving the flagship, and between one and four in Leadership, depending on your spec.
So for a combat build you need to spec up to 3 in Leadership and Technology anyway. You can abstain from Leadership if you're not a perfectionist, don't care about the rest of the fleet at all, and won't miss 15% CR more than you would six skill points elsewhere. This, more than anything, is why high-combat builds are rare.
I have no idea how you'd solve this. I'm not sure it's possible without severely nerfing Tech- and Leadership builds or restructuring these three trees entirely.
Because combat skills are strong. Incredibly so. You can go faster, win the flux wars, quadruple your resistance to EMP damage and recover from broken subsystems twice as fast, penetrate heavy armour with ease, become incredibly resistant to damage even after armour is gone via stacking the minimum damage reduction with the reduced damage to hull, turn on a dime, and boost your damage to fighters and missiles much more than the durability of fighters can possibly be boosted, hit things much more easily via faster projectile and missiles, more maneverable missiles, and better autotracking from high CR. And if you don't have these things, then enemy AI officers have them and make you look bad by comparison. The player can have more of these skills and in a much more optimized layout than AI officers can, particularly enemy ones. Skill perks are a lot like free hullmods that stack with actual hullmod - another factor, incidentally, in how good combat skills are. Missile Expertise and ECCM Module combined are significantly better than one or the other.
A player-controlled flagship with high combat skills can absolutely control the tide of battle around a critical point much more efficiently than anything else, including even carriers with Thunders or whatnot (though Thunders are uncontested in terms of bringing support to smaller turning points in a more spread-out battle, as they are intended to be). I have never even remotely agreed with the notion that Combat is weak and does nothing. With Combat skills, you can chase down most enemies one by one and quickly and efficiently tear them apart, unless they're in a much better ship than you are or also have a high-level officer and fleet support. You can duel the most threatening enemies, control smaller enemies, and let your fleet tear them apart that way. Instead of supporting your fleet to help them defeat the enemy, the fleet supports you to help you defeat the enemy, providing pressure, distractions, and dealing with the stragglers and small stuff. High combat builds are actually really, really fun.
What is true is that a lot of very good Combat skills are available at level one, and that it's much easier to "dip" into Combat than it is Leadership or Technology, which tends to require three points to get the perks you were actually looking for - and which are necessary for an optimal Combat build anyway. And since you do need a fleet no matter what, Leadership and Technology looks better by comparison, and is certainly more reliable, since their effect isn't lost if you overextend and eat a couple of Reapers to the face or otherwise take a devastating flanking or enveloping assault, or if you conversely leave most of your fleet without your support and it gets taken apart piecemeal.
You can't fix this dichotomy by buffing combat (because it would still synergize with tech and leadership with how officers and OP counts work, and giving the fleet's admiral special snowflake bonuses could quickly get ridiculous), unless you do something fancy like make Combat the primary fleet-wide non-carrier combat aptitude (with secondary personal ship effects to keep officers relevant?) and do something completely different with most of Leadership and Technology, completely revamping with new, primarily non-combat focuses which relate to combat about as directly as Industry does.
In any case, you can't easily solve this by adding or removing a skill here or there or changing the numbers around. You'd have to change the paradigm in some fashion, either by making skillpoints more common, or changing how aptitudes themselves work.