That's because the important part of my post is not the specific proposal, but the roles.
Would you think that siege units need to not be able to pillage to differentiate its role from the other land units? Do you ever pillage with a siege unit, by the way?
I do, yes. I tend to set up my siege on pillageable tiles so they can pillage/shoot in a turn if they need to tank 1-2 hits from the city
So, do we agree on the roles, or do you think that ranged naval should be naval skirmishers for a while, then naval archers? Do you think naval melee should be able to take cities on their own, provided they are enough?
Talking about what role dromons and galleases should fill in naval engagements specifically in regards to their IRL counterparts is a bit pointless because neither of these ship types were common or useful enough to comprise an entire naval role in their own time period. Dromons, as they exist in the tech tree, are an anachronism. missiles in naval comabt weren't really popular, much less effective, until the introduction of cannons. The Galleass was a novelty at best. They were far too expensive and there ere far too few of them. They were created by a minor mediterranean power trying to contend primarily with pirates. The shoot'n'scoot role fits these about as well as any other design.
Serious gunnery, with long range engagements and missile weapons destroying vessels, rather than boarding actions, began with the English and Dutch navies in the late 16th century. The warship classification systems, as portrayed by the frigate and corvettes, evolved soon after. At this point, tiered banks of guns still weren't very effective at long ranges. targeting from carefully aimed guns on the top decks of ships was employed in this period, mostly by the French, as a way of harassing enemy ships and damaging them just enough to force them to make expensive repairs, but couldn't ever manage to do enough damage to destroy or disable a ship. For this tech level, the shoot'n'scoot certainly makes the most sense to me.
After that, gunnery, powder, and rifling on cannons makes guns far more accurate and dangerous, even at extreme ranges. Cruisers and battleships could certainly fulfill a naval siege role at these tech levels, with subs and melee filling the gap for the rest. The age of the ironclad was brief, as it didn't take long for cannons to catch up to armor plating. After that, naval engagements between even the smallest military vessels are, at their very closest, hundreds of meters apart. WWII battleships would shell targets at ranges of 5-8km. The Japanese Yamato class had the longest firing range at approx 10km.
With current G proposal, a range 2 frigate with extra range, and maybe indirect fire, is able to defend a coastal city from land attacks 3 tiles inland. The same frigate just needs a swap of a caravel to reveal 3 tiles inland, and then bombard with all ranged naval in range, to dominate 2-3 inland tiles.
However, reducing RCS to half and boosting city damage to 2x would make ranged naval only performing finely against cities and entrenched units. That's fundamentally different. It's not the same an all around unit that fights better at this or that, than a focused unit you absolutely must have against coastal cities but it's not very useful against other units.
Only 2 tiles inland, and they can't move afterwards, so they will have to tank whatever retribution being on a coastline will entail, unlike now. I don't see this as being any sort of problem.
Range was taken off as a valid promotion ages ago, and Indirect fire is locked to battleships, if memory serves; I don't think it is available to naval ranged units, except as a free promotion. The current suggestion is that they won't be able to hit anything but coastal, even with 2 tiles of range. It will functions like hills do to block archers.
As I see it, without a proper exclusive role, both ranged and melee naval would compete for the same things, and there would be always one winner that makes the other unit almost irrelevant. If the roles are too narrow, then the units aren't interesting either, because I might not build the units that only serve for a purpose that I'm not going to use. In that regard, ranged naval could have some support role in coastal defense too, just not killing every unit in sight without retaliation.
Being a ranged unit and being able to hit land targets at all is already a pretty valid basis for a naval role. No matter how dominant a melee navy unit is over its ranged counterpart, it can't project damage inland.