There's another term for this, Sorting Algorithm of Evil, while spectacle creep is probably, if not more politically correct, then a better term for being more generally inclusive of a singular idea.
One question I've always had is, isn't Blizzard aware that this is neccessary? Going from fighting off a demonic invasion to an equivalent zombie appocolypse wouldn't have been as grand if the game before it wasn't setting up the mastermind of that zombie appocolypse to be a credible threat to all life on their world. Going from an ancient dragon god that threatened not only life, but the planet itself to we-weren't-entirely-sure-what-the-badguy-was-until-we-were-weeks-away-from-kicking-his-ass-to-oblivion. Seriously, what the hell were they thinking.
Well thank goodness we've got Call of Duty: Ghosts showing us that a multimillion dollar game can still look like arse. So much for the whole "90% of budget goes into making games 5% prettier" nonsense.
I've been trying to decide if the KotOR series is an example or aversion of spectacle creep. I'm thinking it's an aversion, and if so, the Black Isle/Obsidian team may be masters at this. (Consider Fallouts 1 and 2, then 3 and NV.)
KotOR: The focus of the first game is to save (or conquer) the galaxy (and in doing so, finding yourself). The second game seems to flip that with a much more personal story, where the focus is to find yourself (and in doing so, saving or conquering the galaxy.) I'm still considering the MMO; if it should be considered a proper sequel for this discussion, and if so, whether or not it further averts the trope.
Speaking of Star Wars: Empire Strikes Back showed us that you can still dial back the scale and scope of a sequel considerably and end up creating a franchise favourite. That went from saving the galaxy from a giant planet destroying weapon to being about a guy and a gal on the run from Imperial law and another guy getting training form a small green alien with bad grammar.
You know, every time I watch this episode, and I'm almost reminded of Dragon Ball Z and most other Shonen Jump manga like it.
In the beginning of those stories, the main-heroes are simple and down-to-earth, alongside the challenges they face. But then, as those stories progress, the scale grows so large that it's almost immeasurable. Dragon Ball, for example, started Goku off as a little boy who happened to have super-strength, but of a more down-to-earth kind. The majority of his childhood was spent traveling the world to increase his fighting capabilities, so that he could become the strongest martial-artist on Earth. As a result, the villains were also down-to-earth, from the more comedic Emperor Pilaf, to the Red Ribbon Army, and eventually a demon-king.
After watching this video, I came to realize how much spectacle creep had been influencing my personal opinion about quite a few things. I just really disliked when a franchise would arbitrarily pick out a bigger/badder opponent for it's next installment just for the sake of it being bigger/badder. (especially if it is one that has an ongoing story throughout the franchise)