Back to the topic.
1) It must be the gameplay that bothers these guys. Graphics are terrible, and sometimes players on the field don't act as you think they would (superstar-level players). So, the ingame A.I. still has some problems. And if same glitches happen often they make nerves crack. I also think that with default sliders the game is too much biased to passing and stats show that when there are plenty over 4000 yards/year QBs.
2) It is.
3) I recommend to try sliders (claystones new ones are worth trying and adembroski has also a good set). Sliders make gameplay more challenging and reduce glitches (I don't know how it is that way but they do). After things get too easy with sliders, dig into house rules (insider rule is good). Also not applying points to coaches is what some people do. Whatever you do, don't make it too hard for you first time. It takes restart or two after you notice what you want and can truly start building a franchise.