Do you have (energy) shields in this setting?

@trioxidane Yes but there expensive & rare, with most of the production going to micrometeorite protection for small spacecraft but they are small enough to be carried by a person.

Then it would be like @Demigan his answer, but including shields. Armour makes ranged more difficult to deploy effectively, making melee weapons able to be more effective. Their greater energy output in general and possibility to further improve with special attributes like taser electricity can circumvent some armour as well.

"The slow blade pierces the shield"

@Pootis perhaps you can have a weak shield variant? One that is created within the armor itself to reinforce it rather than one that protects a bubble and prevents any damage.

Just as a warning: justifying melee weapons in a realistic near-future military setting is very difficult without making some major concessions to reality. "Traditionally", melee beats armor, armor beats ranged, and ranged beats melee, but with how good weapons are getting, armor is becoming less and less relevant, negating it's advantage against ranged attackers. A melee weapon makes little sense when a future gun can shoot just as well and accurately at short ranges.

I mean, militaries today use melee weapons only for non-lethal internal enforcement and discipline (batons, nightsticks, etc) and some militaries still use bayonets in a limited fashion (usually for utility purposes though). Besides that, special forces theoretically use things like garrotes or combat knives, but realistically, a modern solider never engages in hand-to-hand cqb against an enemy (even in special forces, cqb is only a minor part of training).

@Demigan sure, but justifying human components in a near-future setting isn't too difficult compared to implementing melee weapon fighting. To justify human relevance in a near future combat setting only requires one "small lie" like "AI has perviously unforseen limits" or "cybernetic neural interfaces are easier than expected" while making melee fighting commonplace requires many more "lies", and not all of them small and many with wider implications on the rest of the Worldbuilding

Light sabers are a melee weapon, for what it's worth.

Well melee and ranged weapons have co-existed since the dawn of time and still do so now in the age of firearms. And they have survived that long because they are useful, even if only on rare occasion. So barring some entirely unforeseen circumstances I see no reason why they wouldn't continue to do so.

Read some Warhammer 40k books, you'll get some good inspiration.

@Dragongeek I don't see the problem, why wouldn't the same unforseen limits be able to account for modern weapons? Hell you can even make it plausible in real life: a flexible Graphene armor across a sturdy frame that spreads the acceleration evenly across the bodypart hit, with mechanical arms to for example absorb hits to the face without whiplash/concussion effects. This would let you wear thin, light but extremely resiliant armor closer to light vehicles than infantry armor. Add a melee weapon capable of cutting it more easily and you are done.

@Demigan yeah, but armor is mostly irrelevant. It's always easier to simply use a more energetic weapon. I mean, the modern soldier has man-portable HEAT missiles that let them singlehandedly destroy basically any armored target, regardless of armor thickness. The armor on battleships, afv's, and other military equipment has been getting thinner since WWII. Even if you had ultra-armor, how can it negate ranged attacks? If there is a material capable of cutting it, why not just tip my bullets or micromissiles with it? Your solution is already wildly unrealistic.

@Dragongeek absolutely not. In WWII rocketlaunchers were still relatively easily man portable, as armor improved you now need teams that carry much larger, heavier, more expensive ammo. If your soldiers have 1 or 2 expensive and bulky shots before they are out of ammo just to be able to kill a soldier in one hit then melee weapons become increasingly more useful. Especially when considering that on average hundreds to hundreds of thousands of shots are fired for a single kill.

@Demigan You're ignoring the fact that offensive technology advances faster than defensive technology. I mean, look at today's high end weaponry. Against a nuke, a hypersonic missile, or a railgun dart, there's no level of armor that will stop it. The only options are pray the PDS works and get out of the way. Yes, if you put a future space-marine in ultra graphene armor they might be virtually immune to some dude with today's M4 or AT missile, but that's not what they'll be facing. They'll be facing someone whos gun fires hypersonic, graphene-tipped, self-guided, etc, munitions.

@Dragongeek It's not true that offensive technology advances faster than defensive technology. They usually go alongside, with minor sprints on one or the other which may favour different approachs to combat. Shaped charges seemed to end the age of armored vehicles by the end of WWII, but now chobham ceramic armor and Active Protection Systems like israeli Trophy have turned the tide around, and anti-tank weapons are abandoning HEAT and going back to high-speed kinetic penetrators.

@Dragongeek these are infantry, they are unlikely to be carrying near-critical fission material with them, or large enough missiles to go hypersonic or fire railgundarts. And by the same token that AI is limited to enforce biologicals as soldiers, so would miniaturized smart-ammo be limited either technologically or through ECM. The point is: any weapon with enough force to penetrate such armors is likely to harm the shooter as well or heavily limit the amount of ammo they can carry. Just because lately firepower increased faster doesnt mean thats the norm. Plate armor times as an example.

easily thought answer is that the world in that near future settings is all covered by thick fog (e.g.: because of pollution/climate change/alien invasion/etc.) that visibility is very poor that you can't properly see very far (therefore cannot aim gun very well). But some people would still use guns because it's now cheaper or because they have very good eye (or equipped with infrared optics that have become very rare commodity).

@DrakeP Yep, but unless you're a Jedi Knight that knows how to use them to block blaster shots at distance, you are dead as "you brought a (light) knife to a gunfight"! :-)

If you want a good example of melee weapons in future settings Warhammer 40K can give you a good example of how that balance works

Does this answer your question? What are the enabling factors for melee combat in modern or future settings?