batsbrew
... 
and it depended on the length of the album,
really long albums tended to be the worst.
 
that said,
i think people just decided they liked the sound of more bass, in general.
which i do not necessarily agree with.

I think it was over blown all along, but the rap thing in the 90's was all BASS and some of it was not exactly musical to our ears.
 
The "longest" LP's I have are, of course Klaus Schulze, but his bass use is very detailed and also well defined and not out of range of the over all music he is playing. He does his own mixing live in performance (check albums with Lisa) and he adjust everything as he sees it fit. You can see the same thing in the albums.
 
Of all the "bass" albums I have, and I do not listen to music because of an instrument at all, there really isn't anything that stands out for me, that had the rock "strength" that things like Led Zep did and a couple of other bands. Hawkwind's Space Ritual was a fave for me ... but there was way too much better music out there for my ears, to worry about one instrument and not the rest of the stuff available. Even DISCO was heavy on the bass, specially in the clubs.

Moshkito
But the only time I saw a needle jump there was because the girl .... accidentally came against it ....

 
Oh my 

sharke

Moshkito
But the only time I saw a needle jump there was because the girl .... accidentally came against it ....

 
Oh my 

Not a joke, either ... I have it on tape and then some! It's hilarious actually!
 

alewgro
Anyone know why?

It's all about the bass?

Three reasons I can think of: Trends, clubs, and affordable sub-woofers.
 
Edit for number 4: Because we can.   
 

Reason #5: Stupid spends money. Let's face it. We're not the sharpest light bulbs in the tool box. Advertising tells us that louder is better and we trip over ourselves to buy louder albums. When that well runs dry, they tell us that bass heavy mud is better and we can't spend our money fast enough. They tell us that a boy band is great, and billions of people devote their lives to them. A year later, that band is lame and a talentless hack wannabe celebrity is the latest thing. We buy everything they offer, dress in their clothes, wear their scent, and change our accents to imitate them. We know this, and we fall for it anyway. We point at other people doing this and laugh at them because it makes us feel better about ourselves. It also helps us maintain the pretense that we haven't fallen prey to the whims of advertisers. 
 
I have to go look at social media now to find out what I'm supposed to like today. 

alewgro
plus there are VERY heavy bass albums released on Vinyl today - I've heard them on Vinyl... they are BASS HEAVY!
 

Yes yes. But bass is not the only thing in a recording. It's been answered a few times already: You can't have all of it on vinyl (normal 33 rpm): Clarity/separation from bottom to the highs, loud enough but with dynamics, and bassy. So the bass heavy vinyls you hear have sacrificed something to make that bassyness possible. 
 
There were special editions of vinyls (I think it's called "direct carving" or something) used especially for classical music. They had a better dynamic separation and a warning on the cover that they may break your loudspeakers.
Also they were manufactured of somehow better vinyl, and they were very expensive.
 
Then were (and still are today, I assume), as mentioned, so called maxi-singles, which are the same size as LP's, but were played 45 rpm. They had better sound as well.
 
I do think that two of the reasons, in addition to the requirements of different genres, were:
- People were not used to overly bassy sounds. Very many thought that reggae sounded stupid.
- In the 60's and 70's especially young people had often very modest sound reproduction systems.
It was useless to make records with deep basses for loudspeakers that couldn't go below 60 Hz and did not have any compensating EQ circuits to protect the loudspeakers. 
I remember once listening Tubular Bells through loudspeakers that went "brrrrrrrrrrrrr" every time the low organ sounds came to picture.

Fishing catch limits were stricter back then and the government accidentally put bass on the endangered species list.

craigb
Fishing catch limits were stricter back then and the government accidentally put bass on the endangered species list.

And the Columbia River will be there soon, before we depart from this earth, with no Salmon coming around anymore, hoping to find habitat's for spawning in such meccas as Jantzen Beach, Vancouver, and some other small areas further towards its end!
 

UbiquitousBubba
Reason #5: Stupid spends money. Let's face it. We're not the sharpest light bulbs in the tool box. Advertising tells us that louder is better and we trip over ourselves to buy louder albums. When that well runs dry, they tell us that bass heavy mud is better and we can't spend our money fast enough. They tell us that a boy band is great, and billions of people devote their lives to them. A year later, that band is lame and a talentless hack wannabe celebrity is the latest thing. We buy everything they offer, dress in their clothes, wear their scent, and change our accents to imitate them. We know this, and we fall for it anyway. We point at other people doing this and laugh at them because it makes us feel better about ourselves. It also helps us maintain the pretense that we haven't fallen prey to the whims of advertisers. 
 
I have to go look at social media now to find out what I'm supposed to like today. 

YES... we have always, at least in this smaller world, been told what to like buy by promoters and others who get rich off it. The same way ties get longer/shorter/thinner/wider. We are told what to like by the people who sell it to us.
 
J