A couple of open thoughts...
1/ NO way should players who don't play regular season play in the playoffs. Aside from stacking a team... I personally could have tried for the 8 seed this season then rolled out a completely different team for the playoffs... I know it doesn't guarantee wins because all the teams would be stacked, but it would cost me NOTHING to try. As stands, there is a decent cost for trying to win in the playoffs; if you want playoff success you have to lose player seasons of eligibility.
2/ I disagree with ideas to lengthen player careers, or juice the draft. The end effect of such types of changes would be more "100" players in the league, getting there faster. While having better players is important for a team to win, and reassuring to us as team managers, more better players lowers the standard of the game. We have all seen that as players increase their ratings, they rarely become better scorers, they become instead better defenders and playmakers. You put two 100s on a line with a 60 and the 60 ends up taking all the shots. The 100s on opposing teams cancel each other out, it's the 60s, 70s and 80s who make the difference.
3/ With that said, the way the sim works now IS that the best, DEEPEST teams win. Which is as it should be, shouldn't it? We have seen owners get there through different means. I have won by developing probably 99% of my own players through the draft, corbs accelerates the process through extensive trading. The reason that I believe the non-playoff and SC bonuses have been disregarded has been that getting one stud player has very little effect on an MLD team, unlike in real life. I actually saying that as reinforcing the need for those bonuses, because teams which end up on the bottom in this league genuinely need team wide infusions of skills.
4/ What I'm hearing is that there's a bit of discomfort with the idea that half the teams in this league are in a Go For It window, and the other half are in Don't Even Try. With the secrets of success being either player development or player acquisition, I don't see any honest way to legislate parity into this league. You're simply always going to have teams at different points in their development cycles, unless some kind of nuclear option was enacted and we rebooted like Star Trek.