Funny that you mention Churchill's smoke because it the current implementation that is not readable or even intuitive. It current implementation is a stock, weird trailed "Panzer Tactician" with a different mechanic in on the most durable tanks in game. One is created by smoke canister on the turret of tank the other form the exhaust.
The name "Infantry Support Smoke", the description "A line of smoke is released behind the Churchill, allowing supporting infantry to advance safely. The Churchill will have reduced speed while deploying smoke" and the role of the vehicle all indicate that Relic was planning to make Churchill's smoke provided bonuses to infantries but was lost to a oversight.
The benefits of specialized smoke are clear. Can be used to make units better in the role and have added utility. In the case making Churchill provide cover status it would increase the synergy of the vehicle with infatry and be helpful in heavy infatry build.
If abilities like smoke in this case provide similar benefits the units bring less to the table making them less disable to build and usually the unit with more DPS is picked.
I mentioned the Churchill's smoke because 1. you also mentioned it in your opening post for potential specialized smoke and 2. it is a functionally clear example of where specialized could be used to enhance gameplay (infantry tank buffs infantry around it). Maybe I was not clear enough, but I was not talking about the Churchill as it is now in CoH2, but rather hypothetically about giving the Churchill "smoke with added buffs" as Relic might have planned.
Think I have provided a very specific proposal, other may add or subtract as they see fit.
Definitely, I just wanted to reinforce that categorizations will always be to a certain degree arbitrary and hard to justify "objectively", hence less intuitive.
I personally do not like the "shot blocker" effect of smoke and I would rather have it replaced from all smoke weapon.
Although I do agree that there benefits in keeping the "simple and understandable" in my opinion the benefits of customizing the effect to specific categories outweigh the benefits of keep the system simple.
The small arms system was very simple and the change to weapon profiles made more complicated. It also improved the game drastically.
Just for clarity: It is still a LOS block. Anyway, I am also not a big fan of it in the cases where you can time the smoke well enough to block LOS just before the enemy tank has reloaded, thereby maximizing micro for the opponent. In other circumstances, it makes pretty much sense. It is a "gamey" component, just like the usage of ground attack in many other cases. CoH is an arcade game, we cannot capture all details.
I think we just disagree on how we estimate the "gameplay improvement vs readability cost" on the matter of smoke.
I am also not sure what small arms change you are talking about, but I guess the introduction of weapon profiles? Assuming this: My point is not necessarily about complication, but readability and intuition. The weapon profiles make, for the most part, sense. MGs are good long range, SMGs short etc. These are self-explanatory even without profound knowledge about weapons. With those weapons we can however see the same thing as with the exemplary abilities I have listed in the last post: If things become similar in name or appearance (by name, description, audiovisual presentation), players will assume they are similar in behaviour. Hence the confusion of different MP40s, G43s, scoped rifles (snipers and e.g. JLI making the same sound and traced smoke line for shots, but function differently). This lowers readability and leads to confusion.
And I don't see how you would be able to make such big differences in smoke that they become self-explanatory. They will be arbitrary. Probably improve gameplay, but still lead to a badly designed ability.