I think the answer is a balance between things. overall the more justice there is the game, the law of nature will prevail and win.
possible
1. things save time:
a. have 10 overs straight from each end. total of 20 overs in an innings. saving of 18 * 45 secs per innings. 13 and half mins. each innings. about 27 mins per match. Nearly half an hour!
b. limit run ups to eg inside the 30 yard circle, thus saving extra long run ups. few secs per ball.
c. have two bowlers bowling at one time, if they have the same action. eg seam bowlers with seam bowlers and slow bowlers with slow bowlers
it allows bowlers with 30 yard run ups to walk back to their mark whilst the second seamer who has a long run to bowl one, and then take in turns till both bowl 6 each finishing a 12 bowl (2) over. keeps the run of play going and the number of action potentials fired per min to increase. (science terminology)
2.
a, have batmans to face a limited number of balls, just like bowlers have 4*6= 24 balls each.
each batsman gets 50 balls max. unless 9 wickets have fallen he can come back after temporarily retiring.
All this easily practiced and proved with children. If they can adjust and have more fun, as the play is almost consistent , then it will be for adults as well.
one thing kids don't like is standing still doing nothing. the two bowlers bowling at the same time allows much more play then one ball per 45 secs. proved to work.
also kids don't like to not bat, if opening batman score a century each or top order i.e top 4 score all the runs what do remaining batsman do? they don't get bat. everyone likes to bat, but with 20 overs we cant have the mindset for a test match or odi, ie. bat till you get out. or overs are bowled out. not fair.
3. have new run system for boundaries:
4 changes to a 5
6 changes to a 7
100 meter + six is given a bonus to 8.
120 meter + six you get a 10.
1 single changes to a 2 and so on till a all run 4 = 5
idea is to allow batsman to reach 100 more so to celebrate a century. bigger scores are more exciting eg 300 scored in 20 overs. etc..
4. make drs 'if its out its out'. Simple. third umpire to intervene if wrong decision is given. Not limit to 1 review per innings. what happens if on the first ball of the innings a batsman wrongly reviews and so the remaining 19.5 overs the team is left with a review, and wrong decisions are given. not fair. reverse also applied if a bowler wrongly appeals on the first ball, so the remaining 19.5 overs no review for the fielding side, and potentially lots of wrong decision not going their way. not fair.
If umpires become less important, so be it. Unless its umpires call, to keep the ' owzat appeal' in the game. The umpires, are are not more important then the game. They are they for the game, not the game for them. Make it perfectly fair, (minus the umpires call bit expect for hitting the wicket. ).
b. if the ball hits the wickets its out, not 49.9% as the error is only 2% not 49.9 % therefore 5% margin is given only on hitting the wickets not for outside leg or outside the line...