I have a far more cynical take: marketers realized a faster-paced game means that in the long run they can sell more product - adventures, splat books, etc. - and influenced (or ordered?) the designers to move in that direction.
My take on this is that more people preferred a faster-paced, reduced-tedium game and the designers listened. If lots of people didn't enjoy those changes, then it wouldn't be as popular as it is.
I mean, how dare the game designers create a game that lots of people enjoy!? They might as well be reaching their greedy little mitts directly into my wallet and helping themselves to the contents thereof! The sheer temerity of it all!
Back in the day, there were dramatically fewer options if the style of a game didn't suit your preferences. Even if the game existed, good luck actually finding a copy unless you had a FLGS in your neighborhood that could get it for you. I didn't, and I remember reading and re-reading Rick Swan's Complete Guide to Role-playing Games as a kid, dreaming of being able to own many of the games described therein. That probably is a significant root cause of why, now that I can order games online, I literally need to add a whole lot more shelving to my office soon because I have stacks of RPG books on the floor reaching almost as high as my waist. It's a nice problem to have.
No game can serve all interests. Back in the older editions, my groups house ruled things to increase the pace. We had more generous rates of natural healing (often something like level + Con HP bonus recovery for long rests) and allowed the creation of non-magical healing balms that cured 1d3 HP, which we stock piled. We allowed leveling mid-adventure. It didn't fix the issues, but it ameliorated them a bit. Nowadays, my group is happy with the pace and doesn't need house rules for them, whereas it sounds like you do (if you want to achieve the style of game you're looking for in 5e, at any rate).
There are in fact a considerable number of games based on 5e that do bring the game into a slower-paced and/or resource-oriented play style. Into the Unknown, Five Torches Deep, King of Dungeons, Adventures in Middle Earth. Moreover, there are a considerable number of fantastic games in that space that aren't based on 5e, such as Worlds Without Number (which just released Cities Without Number if you're looking to do a Cyberpunk/Shadowrun-esque game), Into the Unknown, and Ultraviolet Grasslands. If the folks you're playing with aren't interested in those kinds of games, then I dare say the issue is simply that of a difference of play preferences.