I was one of the testers and I admit that I did not test for
"the problem of If you use the button in league setup to delete career stats It also deletes the team there currently playing for from there stats" 
. I do not mean to imply this is not important, but it
seems like an issue that might only apply to a very small number of users. Maybe I am not understanding it completely but this is actually the first time I have seen the issue raised. If this is a bug that effects many users then I too would like it fixed ASAP of course.
There are many other area's of the game besides this that we would all like refined based on the way each of us play the game. In cases like this one the most simple developer solutions might actually be to
remove the ability to delete career stats completely, so Markus has to weigh the benefits of allowing the user a large amount of freedom within the game's architecture, or refining some key target area's of the game and removing some of the other unrefined area's. I am sure he does not want to remove features that need tweaking, so we are left with some great but maybe incomplete features that require some extra effort (and patience) on our part to take advantage of.
Another example of the games open-ness over refinement is the ability to have 40 teams. There are some unfixed problems associated with having that many teams - should Markus leave the game as is (for now), spend a lot of time refining an area that a majority of users will not even see, or reduce the amount of possible teams to 36 to save a lot of devel time and user complaints? The decision there might be to leave it as it is and flag it as a low priority fix for the future, maybe even for OOTP5.
To me as long as there is a current workaround and the issue only applies to a small percentage of the users then we have to be patient and accept that any gamebreaker bugs or issues/features that impact all users are probably going to be at the head of the line.