1. I have, indeed, played some amateur soccer, and reffed some youth soccer. I'm not very good, needless to say, at either.
2. More importantly, it shouldn't matter whether someone's played a sport for them to spot opportunities to improve it. Lots of people make advancements in fields they previously were not experts in, so long as they study them carefully enough and do their homework.
3. We had a lot of this out in a thread around the time of the World Cup, where DLew and the other BWG veterans made fun of a lot of stupid suggestions people offered. Suggestions to increase the number of refs were among the least-mocked, if I recall. But if you're interested in a discussion of football rules, that thread is a good read.
So to go back to it: Your counter-argument is "more work, more problems"? I'm not sure you appreciate how this hypothetical system would work. As it stands, the ref can issue yellows and reds for conduct that occurs 10 times or more per match, where he'll let some go, give verbal warnings for others, and then escalate if need be. The problem is, that current system of penalties is "chunky" - there is a huge gap in conduct between what is desirable and between what is penalized, because the threshold for that minimum penalty is so high (and yes, there are fouls for direct/indirect kicks, but that's not really what we're talking about). And in that gap is a lot of opportunity to incent players to do things that are more desirable and less (pick your description) dangerous, over-aggressive, un-sporting, etc.
The incentives for players to flop, grab jersey, shove, and do various other things in an attempt to get an edge, are already huge. They happen in the flow of play, on set-pieces, on fast breaks, basically all the time. And the downsides are, unless they go completely overboard and/or injure somebody, they are very unlikely to get carded. What downside? So we get a steady increase in deceptive, un-sporting behavior that drives opposing fans nuts.
Hence the suggestion to have penalties somewhere between a stern glance from the ref, and a yellow/red card. I suggested two - temporary timeouts (with or without replacement, but probably without), and ejection with replacement. Both are less severe than a red card, but more impactful than a yellow card, such that the violator's team gets a disadvantage from the penalty. If you thought about it, you could doubtless come up with more ideas. But there ought to be something in between a red (a dire, enormous penalty) and a yellow ("please, sir, try not to do that quite so much!").
But then, giving referees options like that would require that the refs be able to catch the flopping, grabbing, shoving, and so on. Frankly, you need more refs. I had a post in that GWB rules thread noting that NFL football has like 8 refs for 22 on-field players, basketball has 3 for 10 on-field players, baseball 4 for 10-13 on-field players (6 in the playoffs), hockey 4 for 12 on-ice players... but soccer? 3 for 22 players, a dramatically different ratio. And since the game moves so fast, a single on-field ref, and linesmen who are at least 30 yards away, can't possibly be expected to have a good view of most players most of the time. You need more. Working out the mechanics of how they move around isn't complicated - other sports do it just fine. For important calls, they conference up for a second. One ref is the crew chief who makes final decisions, etc. It doesn't need to become a tornado of whistle-blowing.
