Computers with good SSDs and not too much bloatware (relevant on Windows) do feel faster to me than computers used to be.
I think people can get nostalgic accidentally and overestimate how fast things were in the past. I remember multi-minute loads for games on my Commodore 64. I remember multi-minute Windows 3.1 bootups. I remember watching a JPEG progressively creep in on the early web. I remember watching my school projects in C++ take noticeable time to compile despite what we would now consider their absurdly simple nature. I remember when I was reluctant to click on a 1MB download.
But you do want to avoid having a modern Windows machine on a slow spinning-rust hard drive. Yeow.
I've recently switched from 8GB MBA to 16GB MBP and to be honest, I'm not sure I've noticed any more speed above what's to be expected from any brand new machine before it gets bogged down with shit. My MBA used to be able to handle multiple big programs running in the background - 2 of the Adobe suite + Chrome + small stuff, so I haven't felt much use for the extra juice day-to-day, though I imagine the RAM is useful for video editing etc.
No one's asked me yet why these smaller SSD thingys are so much more expensive than larger hard drives, but I prepared the answer a long time ago:
They make your computer feel 10x faster.
Only cheapskates and the stubborn would pass on an SSD.
Even a year ago I was still going "eeehhhhhh, weeelllll, maaayybee..." but sometime in the last year I'd say we crossed over for any professional. It's no longer a matter of paying $100 for a big-enough spinning rust or $600 for a too-small SSD, now it's more like "Do I want a really fast 512GB or a slow 4TB for the same price?", which are both as of right now ~$150 give or take $30 depending on your quality needs. (I just checked.) That's still quite the spread on size, but you can fit a lot in 512GB.
I think our expectations are just getting higher.
Wirth's law is a computing adage which states that software is getting slower more rapidly than hardware becomes faster.
Most likely not at all. Browser speed has more to do with network speed and browser/website design than your hardware. Browsers and websites still make poor use of multiple cores, and making sites performing well is a never ending chase between designers adding more ads, images and visual effects, browsers trying to figure out tricks to make coping with that possible and developers implementing those tricks.