I dont understand what you mean by "continuity porn", but the series has two stated objectives :
1) Take these iconic characters - particularly the villains - and explore their origins
You just answered your own question. If that sort of thing is an end in itself, if it's forced for the sake of including it rather than emerging organically, then it's continuity porn. "Porn" metaphorically means the gratuitous portrayal of a thing as a self-indulgent exercise without deeper merit.
Granted, what I do in my
Rise of the Federation books is a lot about setting up the foundations of the
Star Trek universe as we'll later know it. I've featured the ancestors of Kirk and Spock, the first contacts with planets like Sauria and Delta, and so forth. But it hasn't been the primary focus except when it served a purpose, when it contributed something meaningful. And I've been careful to avoid going overboard with it and making
everything about foreshadowing the future. For instance, in
Tower of Babel I initially wrote a character as Mr. Scott's ancestor, then changed him to an original character because it would've been one ancestor too much, and there was no good story reason for the character to be a Scott. Instead, I made him a character whose family ties were relevant to the 22nd-century narrative I was telling.
I think that
Gotham's primary goal should be telling a story about the rise of Jim Gordon and the maturing of Bruce Wayne. Laying some foundations for characters who are relevant in the future makes sense, but if
everything is about setting up future Batman enemies and allies, that makes it contrived and artificial and frequently gratuitous. Nods to the future should be done more intermittently, so that they have meaning when they are included. It shouldn't be the overriding goal of the show, because then it's just going through the motions.
Note: I'm not disagreeing with you that telling everyone's origin story is the primary objective of the show. Bruno Heller has made that clear enough in interviews. I'm saying that I disagree with Heller's choice to approach it that way, that it's a contrived, gimmicky, and artificial approach that hurts the show. It would be better to focus on a few key origins -- Gordon, Bruce, Penguin, and the like -- along with other elements of foreshadowing used judiciously and with restraint.
Look at
Smallville, for instance. Although it did introduce a lot of future Superman foes before Clark became Superman, they were spaced out gradually over ten seasons. In early seasons, there were relatively few foreshadowings of Clark's future, and most of his antagonists were original characters. In the early years, it was mostly about Clark, Lana, and Lex heading toward the futures we knew. Lois Lane wasn't introduced until season four, Jimmy Olsen didn't show up until season six, and so on. And when they introduced future Superman villains like Brainiac and Zod, they made each one the sole focus of a season-long arc. They took their time (and would've introduced a lot fewer familiar characters if the show hadn't run so unexpectedly long). They didn't try to cram in a dozen future Superman characters every season, at least not until the later years when they were running out of ideas.
