I think the modern release that has evolved is physically easier on wrist than either the cup wristed delivery that predominated in the 80's, or even the old strokers release where we hit up on the ball at release.  The great timing and resultant pendulum arm swing of the strokers era did not allow most bowlers to develop the ball speed necessary to match up with the higher friction balls of the resin era.  Neither did the cup wristed plant and turn release that allowed some very good bowlers to slow hook the lane effectively during the urethane era. 

I think the most effective releases in todays game are very efficient because they generate revs without fighting gravity.  I do know that I generate more revs with a softer release today than I did 10 years ago when I hadn't yet learned how to rev the ball without hitting up on it.

Ball speed is another matter.  More ball speed is necessary with todays equipment, and the young guys wont be able to maintain the kind of speed when they get older that they have now. 

You are right about ball speed, and weight.  I disagree a bit on what the modern release really is.  The open shouldered cup wristed release came about in the early 80's, and is itself obsolete in the urethane era.  What does remain is a bit later timing with a power step to help increase ball speed.  If you watch the best pros today they are coming much more off the back of the ball to play straighter without losing revs.  A common misconception is that entry angle minimizes deflection.  It is really the release of rotational energy that minimizes deflection.  For example, a big looping slow hook can create 6 degree entry angle while rolling out. However it will deflect more than straighter release that achieves less entry angle, but is still releasing rotational energy. 

You are right regarding entry angle and the fact that most of today's top pros
are coming more up-the- back while retaining revs.  However, most of them
deploy an open shoulder at the top of the backswing (with the balance arm
pointed forward, towards the pins), in contrast to a traditional stroker, who
keeps his/her shoulders more closed- balance arm extended to their side.

Also, today's bowlers (most), get their hand under the ball--either via a cupped wrist or by deploying a bent elbow (or both), which they uncoil at the point of release, causing their wrist to break---like uncoiling a Frisbee, but in a vertical plane, instead.
The only way a traditional stroker (like myself) can effect such a release is to increase lateral spine tilt to allow the ball to be released from just inside the shoulder, provided that I also keep my hand under the ball, just before the release point. In this position, the ball is at its "heaviest", which should assist me in naturally
uncoiling the wrist. I tried this, but my game is 40 years a stroker-lol. How I envy
those that can effect it.

Also, you are 100% correct on the cupped wrist style of the 80's. The major difference between then and today, is that in the 80's, ball motion was more dependent on having very firm fingers at release, which a (fixed) cupped wrist
greatly aided. Fingers are still in play today , but the big rev generator now is the
uncoiling of the wrist at release, released with the assistance of much more
(lateral) spine tilt.