I would maintain that DE and WR are very similar, you have just as many reaches because teams are eager to fill those crucial positions and can fool themselves by putting too much weight in workout numbers. You can go pick out five-ten players on each list that were huge risks even without the benefit of foresight and that is because of this tendency.
What can you say is a "quality starter"?
That's neither here nor there. Fact is, if you just compared OL and WR, that's not really debateable. Instead you applied fuzzy logic and math to an inexact science and tried to pawn it off as fact.
Receivers have many factors which determine how they are graded and analyzed, linemen are much simpler in that respect. If you go back in this thread, that's a simple point I made quite a while ago.
OL are easier to grade and their significance/success is less reliant on other factors. WR are often in higher demand, are reached for more often and their success can and does rely on who is delivering them the football and the type of offense being run. Receivers often have to face several years of development, even the great ones. Jerry Rice himself was not great his rookie year. They are at the mercy of many other factors. Linemen have it much simple and are easier to spot in terms of their feasibility at the next level.
Your analysis proves nothing other than the fact that the WR position is more difficult to analyse and that teams push choices at the position hoping to hit gold.
Fear should only enter into the equation if you believe the team is hell bent on selecting a WR. Typically, no matter the overall talent of the draft class, teams draft anywhere from 5-7 in the round, it is just what happens. In those numbers, you will have a reach or two. I doubt that occurs this year with perhaps one of the deepest and most talented groups of the last decade.
We aren't in that position.