DRS, KERS, Pirellis, less wings, higher rear wing, wider front-wing, etc were introduced as solutions to processional races..Take them out then we will be back to were we were before..then all of us will complain about boring races.
So you think all the drivers are not pushing hard or racing hard enough? Maybe some but not all..but I think it's more due to the fact that their car design is not well-suited to maximize the potentials of the current tyres.
Ok, the chronology of the elements you mention, if I remember correctly, was the following:
1. Lack of overtakings and generally boring races spark the Overtaking Group (or something like that). They consult the fans (I remember filling out the questionnaire) and decide to change the rules for 2009. You will clearly remember this as the front wings became wider and the back wings taller (and people thought the cars looked horrible). Great expectations, the turbulence behind a car will be reduced, allowing closer racing.
2. Brawn find a loophole with DDs which is not banned in time, which also creates too much turbulence. Everyone copies it, new rules negated. They ban it for 2010.
3. With DDs banned for 2011, supposedly the original idea of 2009 had its first chance to show if it worked. Did they even test it? No, they introduced DRS right away. Teams come up with BEs. Cars still produce too much turbulence, overtaking still difficult, objectives not reached. BEs banned for 2012.
4. Never having even tried the original configuration suggested for 2009, they keep DRS and further manipulate the tyres. At the end of the day you can see that instead of trying to keep at their original objective of reducing turbulence by changing mainly aero, they have not kept at it and instead introduced these artificial elements. If the aero changes for 2009 did not work or did not work well enough, there was always the chance of fiddling with wings some more (heights, widths, complexity, etc.). Why they didn't do it is the real question.
To answer your other question, I think that maybe the small differences we see between teams are not due to some magic jump forward that has allowed the midfield teams to catch up (as Pirelli, FIA and excited star-eyed fans want to make believe or believe). Because no one is able to push at 100% the differences become smaller, as the difference between, say, a McLAren and a Sauber, can't materialize because, at less then 100% performance, these cars are closer in speed (as when you pedal slower so that your son can keep up with you on your bikes). Add to that the roulette resulting from parc ferme and changing weather, the super narrow window of the Pirelli cheese and the inability of drivers to pull more than one attacking or defending move and indeed you have a very close, but artificial, field.