The '70s and 80's

"It's also a reference to how those two decades (the latter more than the former, tho) sucked. "

Or it could be a reference to people who give their opinions as truth when in fact they don't really know anything about the matter, first hand.

Austin never visited the 70's or the 80's (except in the third movie, briefly - and even then only the 70's), so he doesn't really know what it was like. Perhaps the joke is that SO much happened during those decades, and SO much magic manifested and exploded into various forms of energy especially during the 80's, and then Austin just discards 20 years worth full of interesting stuff as "That's about it".

The contrast between Austin's mundane misconception and the adventure-filled unique and eventful reality is pretty funny.

Also, those decades definitely did not suck - they were much better than any decade after that (though we only now know about two fully and a little bit of the third so far). Like they say, "I liked the old millennium better".

What's curious to me, how -anyone- can compare 70's and 80's and choose the SEVENTIES as the better one - they didn't even have personal computers or energetic 80's musics in the seventies!

The 'feel' was also much more mundane, clumsy and boring in all areas of life, there was no 'flow' in the seventies, like there was in the 80's. Sure, there were lots of druggies, hippies and such - so maybe if you were trippin' with them, perhaps 70's seemed like a good time. But I'd say seventies was like a pale shadow compared to the magical magnificence of the glorious 80's, and if I had a time machine, I would set it to loop from the beginning of the 80's until the end of the 80's, and then jump back to the beginning .. and loop that cycle until I die.

Seventies was 'ok', but 80's was 'marvellous', 'fantastic', 'superb' and 'cosmic'!

And as I said, neither of those decades sucked, so you are only offering an (uniquely unbased, weirdly biased and completely unexplained) opinion here, not the truth, so it might have been a good idea to add "In my opinion" in the beginning of your otherwise incorrect statement.