Are there problems with they way LE is tasked and deployed in present-day America? I'd say yes. For one thing I think far too much time is wasted worrying about trivia like marijuana possession. For another I think police powers have been increased far too much in the name of the War on Some Drugs.
However, your characterization of cops as cowards is grossly inaccurate. I could fill pages and pages with anecdotes about officers I worked with doing courageous things. Out of a couple hundred cops I've known personally, I've only known one who was a coward, and two or three who were definitely bullies.
Cops are people, and like any other group of people there are the good, the mediocre, and the suck. In my experience there's more good than mediocre, and the truly unfit are not so common as you imply.
If you have a problem with the laws officers enforce, talk to your politicians. If you have a problem with the way officers engage in stops and searches, talk to a judge (they set most of the parameters cops work with in that regard).
You obviously have a strong resentment against authority and those who enforce the law. This is not unusual... Americans more than most other people don't like being told what to do, or questioned or detained. That's fine too... we should always stand up for our rights. For example, I NEVER consent to a search... but I decline politely. I've been out of the LE biz for a dozen years, and yeah I've been stopped and questioned several times about one thing or another. Most of my LE encounters were not bad experiences; a lot of times the attitude you encounter in the cop will be a mirror of the attitude you exhibit towards them in the first moments of the stop.
Your assertions that the majority of cops are bullies and cowards is based on second- and third-hand heresay and a few unpleasant traffic stops or sensationalized news stories. My assertions are based on having done it for several years, having known hundreds of LEO's and dealt with many both as an LE and as a private citizen. I'll let the readers decide who they think is more credible.