I think I would like an ongoing title that has stories about romance with just the superheroes of Marvel or DC. 

While there are advantages to serials that end, I don't believe that you can't write interesting stories with existing characters. Whether it sells and gets the support it deserves is another story, but I do want to touch on the point about putting the characters back in the box. I don't know if it's comic book courtesy or a way for creative teams to ensure that their work isn't retconned but at least it provides some closure. An interesting concept that came up in a Marvel book I was reading lately was referring to the reboots as seasons. Since modern comics draw so much inspiration from television, it makes the resets easier to understand. 

As a kid, it didn’t put me off reading, say, Batman #400. I also am not sure why comicbook publishers feel they need to copy TV, but I know people’s mileage varies.

Have there been any increases in sales, though? I can understand them chasing that audience if it has led to an increase in sales, but part of me thinks that mindset (from the industry, not from you) is akin to Vince Russo’s strawman of “chase the casual wrestling audience”.

We can only go by the circles we mix in, but as far as people I have spoken with, who came to Marvel via the MCU, when I’ve asked, not one of them has expressed any interest when I’ve encouraged them to check out the comics. One friend watched the various MCU films in order over the last 6 months or so, yet when I asked him if he’d consider checking out the comics, he wasn’t interested.

Long-term fans like those on this forum will embrace overlap, but I am just wondering, if the “TV viewer who might check out a Marvel comic” is akin to Russo’s strawman. Is there any evidence of it?

Asking questions as much as making statements here, always happy to learn.

I’m glad you asked how many casual readers of any kind of magazine exist.

Former WWF writer Vince Russo is forever asking why WWE, which is a profitable company, isn’t chasing the ‘casual fan’. His strawman (IMO) is that there exists this casual wrestling fan who needs to be persuaded to give WWE a go. I’m not sure WWE should be chasing casual fans, any more than, say, HBO or Kellogg’s Cereal should be. Isn’t concentrating on the fans you have more important?

I’ve heard people some say that these ‘number one’ issues are to attract new readers, but I’d love to see evidence that a) these people exist (some might), and b) the ‘casual fan’ who would buy such an issue stays on board.

Is the idea of a casual fan/reader/viewer a strawman?

Here's the thing; you can't have growth without a new audience.  That applies to any kind of medium; so, even the WWE has to attract someone other than the established audience,.  Failing that, they can only increase revenue by trying to wring more and more out of their existing audience; but, there comes a saturation point and then you start losing your audience.  S, inevitably, your audience will start to shrink, without new blood; either your existing audience just leaves or they age out.  That was the death of many territories, in wrestling, before the WWF expansion.  Places like Indianapolis and Detroit just kept doing the same thing, for the same audience and some got tired and stopped watching and attending matches and others just got old and died or outgrew their interest.  Younger fans didn't seem to care for their product, so parents didn't take them to the shows.  The end result was that they went out of business on their own, though Cable sped things up, a bit, by offering a better product.

Comics were the same way.  By the 1970s, young kids had other entertainments and more affordable ones and comics weren't replacing the readers they lost.  Add to that fewer newsstands carrying comics, because the retailer profit was much smaller, compared to adult magazines (not skin mags, but those bought by adults) and they just didn't bother with comics.  They were in desperate straits until they got an influx of interest from Star Wars, at Marvel, and the Superman film, at DC.  That combined with a new distribution system that allowed them to sell to specialty retailers, on a non-returnable basis, meaning guaranteed sales, based on the retailer's orders.  They could better target series to the audience and get quicker feedback and increase profitability by not having to over-print, as with newsstand distribution.  Comic shops allowed for "remainders" to be available beyond the original lifespan of the issue, at discount or collectible prices, depending on demand.  That saved comics from near-death, by most accounts at DC and Marvel (Harvey was in really bad shape, and Charlton was all but dead and Gold Key was getting there, with Archie maintaining a small, but steady presence on newsstands and supermarkets).  So, the companies turned more and more of their publication over to that system, but at the expense of appealing to a broader market.  It proved more viable, in the short term, but a death sentence, in the long run, without attracting a new audience.

Manga was able to capture that younger audience, for a while, but their sales aren't what they once were, either; just stronger than American publishers, with that demographic; plus, YA book publishing snapped up the rest, who read for entertainment.  Video games took away a certain segment of youth audience, home video a bit and the internet much of the rest.

Regardless of whether you are appealing to a wide audience or a niche audience, you have to excite them about your product and get them to putdown their money on it.  Sometimes, that means taking chances, which is not something that big conglomerates contemplate, unless their situation is getting desperate and they have nothing to lose.  DC was in that position in the late 70s, which helped Jenette Kahn implement a lot of changes, to incentivize creative work and innovation.  She was willing to take risks, because they had nowhere to go, but up.  Marvel did, too, but not to as wide an extent and some of their initiatives were in reaction to DC.  The WWF, in the mid-late 90s was having major problems drawing and was losing talent to better offers.  Vince took a gamble and shook up the organization and backed a new star, in Steve Austin and saw a massive upswing in business and became competitive again and then destroyed his competition (which was more of a murder-suicide, as WCW was cutting their own throat; Vince just helped sharpen the knife).