So I've been playing WF on and off since 2013. And for the most part, we've used hit-scan systems for firearms. And I can see the advantages. Hit-scan in general places less load on the system than projectile weaponry. And it's easier to get into than projectile. But I feel like we have to start moving away from hit-scan weapons. I'd like to justify the reasons why.
First, let's address the idea that projectile trajectory calculation takes up more resources than hitscan. The concern would be that 4 players surrounded by hundreds of grineer firing at you would demand a lot more from your computer if they all had to calculate projectile arc and flight time. To this I'd like to point out that I mean Battlefield 2's Refractor engine did projectile physics in 2005, and we know Evolution Engine is more powerful than that. We also know that the game in its current state can actually handle that stress since we have 4-man squads surrounded by hundreds of Corpus, and Corpus use projectile weaponry. I get that some people are on potato PCs, and projectile physics might be too much for them, but given I'm still capable of running said corpus Sorties and Toroid farms on an i3 and i5 laptop without any real hardcore graphics chipset (granted, at minimum settings), I'd say Evolution is well-built enough and generous enough to previous generations it would make no difference. And even if it did, I'd argue that Warframe has been keeping its engine up with the times enough to warrant saying "it's time to get a better machine."
Second, from a gameplay perspective, I think bullet drop and physics matters as well. Adding bullet drop and travel time encourages mobility to avoid damage. We're getting damage scaling updates soon, and enemy accuracy is being looked at as well. If the goal is to address scaling, then it is best to increase difficulty through mechanics rather than raw numbers. This would matter most in open areas like Plains and Vallis, and I think would go well with the adjustments we're getting. It just feels unfair to have Grineer hit you with sweet sweet accuracy despite the fact you're 300 meters away and mid-bullet jump. It would be great for consistency, and it may open up avenues for projectile speed mods in loadouts while also making the range indicators on scopes feel useful.
Third, most people use projectile weapons anyway. The Ignis, the the Lenz, the Catchmoon, the Boltors, Corinth... so I don't think it would make anyone particularly mad just because they had to aim a little bit more for the sake of actually challenging gunplay.
And on a personal level I feel it would be more immersive. Yeah I get the argument of "If you want realism, why are you playing a game about space ninjas and magic?" Immersion is about internal realism and consistency; how well the content follows the rules of that content. And we know bullets travel. They don't teleport. They even have projectile art even if they are hitscan, so it feels inconsistent to see the impact before the art makes contact.
Anyway, just a few points. I'm probably not alone in this, and honestly I'm not sure how many people actually care. But this is a feedback thread so... here goes.