Ooooo! I could get in SO much trouble with this topic! [:-][8D]
Just sticking to bows, because that's where most of the change has been...
Today's stuff isn't 'better' by any stretch, just faster. Compared to the older stuff, today's compounds are:
Harder to tune. The older, slower bows had a much wider tuning window and would shoot well even if they weren't perfectly tuned. Today, if it's not perfectly tuned, it's not going to shoot worth a hoot. Don't bump that rest while out hunting or your hunt is over until you can retune the bow!
Much less forgiving of shooting form errors. Risers with reflexed handles magnify any torque in your grip and there goes accuracy. Most bows back in the day were made with deflexed grips, which robbed speed but made them darn hard to torque and much easier to shoot accurately under field conditions, in the heat of the moment.
Harder and/or more expensive to maintain. You have to have a full function bow press to disassemble a bow today, where all we needed to do back then was back out the limb bolts. So, most folks can't properly maintain their bows without taking them to a bow shop and paying to get them serviced.
I could go on and on about this, but I'm sure I've thrown enough fuel out there for the flamers to work with.
I began bowhunting before compounds were invented and, honestly, never did get to the point where I trusted compounds enough to seriously hunt with them. I liked shooting competition with them, but what I learned about their reliability on the tournament trail was enough to insure I almost always hunted with longbows or recurves. Even worse, I am even less enthused about the reliability of today's compounds than I was with what we had 20 years ago.