petermc
I think it has less to do with time and age (at least not in the last 40-50 years) but more with your socio-economic background and simply the environment you grew up in etc.
It's imho a false receiption that in the 80s, or 90s or the early 00s there were only sex symbols with big tits. Maybe you only remember those who you were personally into at that time but it doesn't mean that there weren't a lot of females with rather small or medium sized boobs during the last 40 or 50 years who were generally perceived as sex symbols at the time.
Take e.g. Sharon Stone, Kim Basinger, Cindy Crawford, Demi Moore, Julia Roberts, Sarah Michelle Gellar, Kelly LeBrock, Brooke Shields, Liv Tyler, Bo Derek, Carrie Fisher, Michelle Pfeiffer, Denise Richards, Emmanuelle Béart and many more. Some of them had smaller boobs and some of them bigger boobs. Almost zero of them had giant tits or even giant fake tits or whatever.
It's right thought that during the 90s and early 20s big tits were trendy, but imho only in the porn industry and the blue-collar boulevard (like the UK yellow press you mentioned). I'm not sure whether this was a reaction to huge demand for huge tits bakc then or rather a reaction to growing possiblities of getting huge tits due to the upcoming surgery options. Imho it was a rather short time though, maybe lasted 5-10 years top. And I guess it's also a national or rather local question since in the UK, for example, big tits still seem to be much more popular than e.g. here in Germany. But I guess there is some kind of more in-depth scientific research to be made on the topic, it's a lot of guessing involved here...
And since you mentioned Erika Eleniak: she had "only" medium-sized boobs. They were just very well presented (and pretty jammed) in these red swim suits... 😉
I'd bet a huge majority of guys would say that she has a fucking hot body now as they had said it like 20 years ago... 😉