Speed limits may appear to be arbitrarily low. Certainly they could in certain situations (locations) be slightly greater. The problem with increasing a speed limit is that as you noted majority of people drive above the current speed limits. As a driver you need to always drive at speed which will allow you to stop if a stop is so required. The majority of drivers that speed do not follow that philosophy; they never slow regardless of the situation. They are constantly driving/riding above the posted speed limit, why? They believe that they are good drivers. You can’t hope for the best! You have to prepare for the worst and hope for the best! If you can’t see ahead because of bushes, a building or a curve, then slow to a speed that will allow you to stop. That may mean that you slow to the speed maximum if you were speeding or even possibly below the speed maximum. The majority of driver/riders do not do this; if something goes wrong they don’t have the opportunity to avoid the collision.
According to the statistics presented by the government of Ontario (ORSAR 2011), the leading cause of collisions is drivers performing properly. That is preposterous!!! Someone had to make a mistake in order for the incident to occur. If people currently refuse to own their mistakes, how is increasing the current speed limits going to improve the situation? If you and others help me in my campaign to make sure that only skilled, attentive and courteous drivers are allowed to drive on our roads, then I will support your idea to increase speed limits (on certain roads).
You then move to the lowly stop line. It doesn’t get the respect that it justly deserves. The stop line is not set-up to be too far back as you propose. It is placed where it is to keep you and your vehicle away from the crosswalk; the crosswalk is for pedestrians not vehicles. You then mention the two-step process; you know about it, how about doing it. Performing the two-step stop requires seconds longer than the simpler one-step, but I prevents so many problems.
On the approach to an intersection your view of the intersection may be blocked by bushes, poles, electrical boxes, buildings or your own vehicle (A-pillars in a caged vehicle). Resulting from this visual obstruction, you can miss a pedestrian close to the intersection or worse in the intersection. Even if you don’t see a pedestrian, they along with vehicle traffic may be out of your field of view on the approach (aforementioned visual obstructions). If you stop in the proper place, look for pedestrians; if there truly aren't any nearby you can then proceed to the next level. If you can see the intersection, your manoeuvre is legal and there isn't any traffic nearby then you can proceed. If you cannot see far then you can legally move up and block the crosswalk allowing you to see further, therefore having all of the information to make the correct choice.
When you stop past the stop line you not only create problems for pedestrians, but also other drivers. Stopping past the stop line, doesn't allow others to have full viewing access of the intersection even though they may have the right of way over you. They will then have to adjust for your mistake. Further, a skilled driver will not only have to adjust to the visual blockage that you create but they will also have to focus on you because you have now become a hazard; there is less space between you and them then there should be so if you move there isn't time to avoid incident if they don't do anything so they are forced to adjust.
People tend to drive like robots; badly programmed robots. You can drive above the posted speed limit or stop past the stop line if you have good vehicle control, good observation skills and above everything else, good decision skills. Unfortunately contrary to what majority of people believe they do not, nor cannot have above average abilities; that is a mathematical impossibility. Our roads are full of bad drivers; the solution is not to give in to mediocrity but to improve the quality of drivers that we allow the privilege to drive or ride.