Given how the studio panicked after ASM 2, it didn't really seem like they had much vision.and this is where we might all have common ground- i can see sony wanting to hold on to the one element that was universally loved (though its debatable whether it was stone herself or the all-too-real chemistry between her and garfield).
if you want to argue from a point of story cohesion that losing gwen is problematic, i can agree.
but from a production or studio pov? not so much. just ditch webb's vision for the franchise, bring stone back in asm 3. clone her, make it a bad dream, give her powers- superhero comics are not the only ones that can play at that game. the transformers franchise shat itself after the backlash from killing off optimus prime in the 80s and brought him back twice (and liked it so much they've made a running theme of it ever since). if sony wanted emma to continue being in the films, sony would do it. she would most likely have been contracted for more than 2 films anyway (which also points to how the thought process on that side of the camera works. think about that for a second). it would not be an issue. the issue was whether the ASM brand image was already too damaged. it's a cumulative effect starting from ASM 1.
as much as i admire yours and confuzzled's purist approach to story telling, and as much as i wish things would work that way, they often don't. especially in film and tv. often you're learning brand new lines inserted into a script on the morning of a shoot and you have no idea why.
"gladiator" shot without a bloody script and that thing won five academy awards. "stength and honour"? that's russ' high school motto- he just chucked it in there to sound cool.