[kirtar]

I've had a slightly different experience than you have, it seems. At the regionals I attended, scores did increase overall, but usually not as significantly has you have described (except when say, an opposing alliance's defense bot was dead then entire match). As for usefulness in eliminations, it varies. I saw a few matches at Boilermaker in which 2081 hanging decided the match. Also, as a side effect of hanging, if the opponents play defense too aggressively, they may get a penalty (or in the case of Finals match 1 at BMR, a red card).

Under the assumption of a constant rate of scoring, 20 seconds for 2 points is actually fairly efficient if you actually only take 20 seconds since you get what is usually more than 1/6 of the total score for you alliance in 1/6 of the time.